,illustration3 ,,plate ,i4 ,maps        
,i4-,,iv4    ,,half-,,hours  ,,with     
,,the ,,telescope2  ,,being ,a ,,popular
 ,,guide ,,to ,,the ,,use ,,of ,,the    
,,telescope ,,as ,a ,,means ,,of        
,,amusement ,,and ,,instruction4  ,,by  
,,richard ,a4 ,,proctor1 ,b4,a41        
,f4,r4,a4,s41 ,,author ,,of ,,saturn    
,,and ,,its ,,system1 ,,etc4  ,,with    
,,illustrations ,,on ,,stone ,,and      
,,wood4          99       99       99   
99       99      ,an undevout astronomer
 is mad3     ,true1 all things speak a  
,god2 but1 in the small     ,men trace  
out ,him3 in great ,he seizes man4      
,,young4         99       99       99   
99       99  ,,new ,,york3  ,g4,p4      
,,putnam',s ,,sons4  #ahgc4  ,,london3  
,,printed ,,by ,,william ,,clowes ,,and 
,,sons1 ,,stamford ,,street ,,and       
,,charing ,,cross4     ,,preface4   ,the
 object which the ,author and ,publisher
 of this little work have proposed to   
themselves1 has been the production1 at 
a moderate price1 of a useful and       

reliable guide to the amateur           
telescopist4  ,among the celestial      
phenomena described or figured in this  
treatise1 by far the larger number may  
be profitably examined with small       
telescopes1 and there are none which are
 beyond the range of a good #c-;inch    
achromatic4  ,the work also treats of   
the construction of telescopes1 the     
nature and use of star-maps1 and other  
subjects connected with the requirements
 of amateur observers4  ,r4,a4,p4       
,january1 #ahfh4     ,,contents4        
,,chapter ,i4                           
,,page ,a ,,half-,,hour ,,on ,,the      
,,structure ,,of ,,the ,,telescope      
#a  ,,chapter ,,ii4 ,a ,,half-,,hour    
,,with ,,orion1 ,,lepus1 ,,taurus1      
,,etc4           #cc  ,,chapter ,,iii4  
,a ,,half-,,hour ,,with ,,lyra1         
,,hercules1 ,,corvus1 ,,crater1 ,,etc4  
#dg  ,,chapter ,,iv4 ,a ,,half-,,hour   
,,with ,,bootes1 ,,scorpio1 ,,ophiuchus1
 ,,etc4     #ef  ,,chapter ,v4 ,a       
,,half-,,hour ,,with ,,andromeda1       

,,cygnus1 ,,etc4              #ff       
,,chapter ,,vi4 ,,half-,,hours ,,with   
,,the ,,planets                         
#gd  ,,chapter ,,vii4 ,,half-,,hours    
,,with ,,the ,,sun ,,and ,,moon         
#ic     ,,description ,,of ,,plates4    
,,plate ,i4--,frontispiece4  ,this plate
 presents the aspect of the heavens at  
the four seasons1 dealt with in         
,chapters ,,ii41 ,,iii41 ,,iv41 and ,v4 
,in each map of this plate the central  
point represents the point vertically   
over the observer's head1 and the       
circumference represents his horizon4   
,the plan of each map is such that the  
direction of a star or constellation1 as
 respects the compass-points1 and its   
elevation1 also1 above the horizon1 at  
the given season1 can be at once        
determined4 ,two illustrations of the   
use of the maps will serve to explain   
their nature better than any detailed   
description4 ,suppose first1 that--at   
one of the hours named under ,map       
,i4--the observer wishes to find ,castor

 and ,pollux3--,turning to ,map ,i4 he  
sees that these stars lie in the lower  
left-hand quadrant1 and very nearly     
towards the point marked ,s4,e42 that   
is1 they are to be looked for on the sky
 towards the south-east4 ,also1 it is   
seen that the two stars lie about       
one-fourth of the way from the centre   
towards the circumference4 ,hence1 on   
the sky1 the stars will be found about  
one-fourth of the way from the zenith   
towards the horizon3 ,castor will be    
seen immediately above ,pollux4 ,next1  
suppose that at one of the hours named  
the observer wishes to learn what stars 
are visible towards the west and        
north-west3--,turning the map until the 
portion of the circumference marked ,w  
444 ,n4,w4 is lowermost1 he sees that in
 the direction named the square of      
,pegasus lies not very high above the   
horizon1 one diagonal of the square     
being vertical1 the other nearly        
horizontal4 ,above the square is        
,andromeda1 to the right of which lies  

,cassiopeia1 the stars beta and epsilon 
of this constellation lying directly    
towards the north-west1 while the star  
alpha lies almost exactly midway between
 the zenith and the horizon4 ,above     
,andromeda1 a little towards the left1  
lies ,perseus1 ,algol being almost      
exactly towards the west and one-third  
of the way from the zenith towards the  
horizon 7because one-third of the way   
from the centre towards the             
circumference of the map74 ,almost      
exactly in the zenith is the star delta 
,aurig4  ,the four maps are miniatures  
of ,maps ,i41 ,,iv41 ,,vii41 and ,x4 of 
my ',constellation ,seasons1'           
fourth-magnitude stars1 however1 being  
omitted4   ,,plates ,,ii41 ,,iii41      
,,iv41 and ,v41 illustrating ,chapters  
,,ii41 ,,iii41 ,,iv41 and ,v4  ,plates  
,,ii4 and ,,iv4 contain four star-maps4 
,they not only serve to indicate the    
configuration of certain important      
star-groups1 but they illustrate the    
construction of maps1 such as the       

observer should make for himself when he
 wishes to obtain an accurate knowledge 
of particular regions of the sky4 ,they 
are all made to one scale1 and on the   
conical projection--the simplest and    
best of all projections for maps of this
 sort4 ,the way in which the meridians  
and parallels for this projection are   
laid down is described in my ',handbook 
of the ,stars4' ,with a little practice 
a few minutes will suffice for sweeping 
out the equidistant circular arcs which 
mark the parallels and ruling in the    
straight meridians4  ,the dotted line   
across three of the maps represents a   
portion of the horizontal circle midway 
between the zenith and the horizon at   
the hour at which the map is supposed to
 be used4 ,at other hours1 of course1   
this line would be differently situated4
  ,plates ,,iii4 and ,v4 represent      
fifty-two of the objects mentioned in   
the above-named chapters4 ,as reference 
is made to these figures in the text1   
little comment is here required4 ,it is 

to be remarked1 however1 that the       
circles1 and especially the small       
circles1 do not represent the whole of  
the telescope's field of view1 only a   
small portion of it4 ,the object of     
these figures is to enable the observer 
to know what to expect when he turns his
 telescope towards a difficult double   
star4 ,many of the objects depicted are 
very easy doubles3 these are given as   
objects of reference4 ,the observer     
having seen the correspondence between  
an easy double and its picture1 as      
respects the relation between the line  
joining the components and the apparent 
path of the double across the           
telescope's field of view1 will know how
 to interpret the picture of a difficult
 double in this respect4 ,and as all the
 small figures are drawn to one scale1  
he will also know how far apart he may  
expect to find the components of a      
difficult double4 ,thus he will have an 
exact conception of the sort of         
duplicity he is to look for1 and this   

is--crede experto--a great step towards 
the detection of the star's duplicity4  
,,plates ,,vi4 and ,,vii41 illustrating 
,chapters ,,vi4 and ,,vii4  ,the views  
of ,mercury1 ,venus1 and ,mars in these 
plates 7except the smaller view of      
,jupiter in ,plate ,,vii47 are supposed 
to be seen with the same power4  ,the   
observer must not expect to see the     
details presented in the views of ,mars 
with anything like the distinctness ,i  
have here given to them4 ,if he place   
the plate at a distance of six or seven 
yards he will see the views more nearly 
as ,mars is likely to appear in a good  
three-inch aperture4  ,the chart of     
,mars is a reduction of one ,i have     
constructed from views by ,mr4 ,dawes4  
,i believe that nearly all the features 
included in the chart are permanent1    
though not always visible4 ,i take this 
opportunity of noting that the eighteen 
orthographic pictures of ,mars presented
 with my shilling chart are to be looked
 on rather as maps than as representing 

telescopic views4 ,they illustrate      
usefully the varying presentation of    
,mars towards the earth4 ,the observer  
can obtain other such illustrations for 
himself by filling in outlines1 traced  
from those given at the foot of ,plate  
,,vi41 with details from the chart4 ,it 
is to be noted that ,mars varies in     
presentation1 not only as respects the  
greater or less opening out of his      
equator towards the north or south1 but 
as respects the apparent slope of his   
polar axis to the right or left4 ,the   
four projections as shown1 or inverted1 
or seen from the back of the plate 7held
 up to the light7 give presentations of 
,mars towards the sun at twelve periods 
of the ,martial year1--viz41 at the     
autumnal and vernal equinoxes1 at the   
two solstices1 and at intermediate      
periods corresponding to our terrestrial
 months4  ,in fact1 by means of these   
projections one might readily form a    
series of sun-views of ,mars resembling 
my ',sun-views of the ,earth4'  ,in the 

first view of ,jupiter it is to be      
remarked that the three satellites      
outside the disc are supposed to be     
moving in directions appreciably        
parallel to the belts on the disc--the  
upper satellites from right to left1 the
 lower one from left to right4 ,in      
general the satellites1 when so near to 
the disc1 are not seen in a straight    
line1 as the three shown in the figure  
happen to be4 ,of the three spots on the
 disc1 the faintest is a satellite1 the 
neighbouring dark spot its shadow1 the  
other dark spot the shadow of the       
satellite close to the planet's disc4   
,,half-,,hours ,,with ,,the ,,telescope4
     ,,chapter ,i4  ,a ,,half-,,hour    
,,on ,,the ,,structure ,,of ,,the       
,,telescope4   ,there are few           
instruments which yield more pleasure   
and instruction than the ,telescope4    
,even a small telescope--only an inch   
and a half or two inches1 perhaps1 in   
aperture--will serve to supply          
profitable amusement to those who know  

how to apply its powers4 ,i have often  
seen with pleasure the surprise with    
which the performance even of an        
opera-glass1 well steadied1 and directed
 towards certain parts of the heavens1  
has been witnessed by those who have    
supposed that nothing but an expensive  
and colossal telescope could afford any 
views of interest4 ,but a               
well-constructed achromatic of two or   
three inches in aperture will not merely
 supply amusement and instruction1--it  
may be made to do useful work4  ,the    
student of astronomy is often deterred  
from telescopic observation by the      
thought that in a field wherein so many 
have laboured1 with abilities and means 
perhaps far surpassing those he may     
possess1 he is little likely to reap    
results of any utility4 ,he argues that1
 since the planets1 stars1 and nebul    
have been scanned by ,herschel and      
,rosse1 with their gigantic mirrors1 and
 at ,pulkova and ,greenwich with        
refractors whose construction has taxed 

to the utmost the ingenuity of the      
optician and mechanic1 it must be       
utterly useless for an unpractised      
observer to direct a telescope of       
moderate power to the examination of    
these objects4  ,now1 passing over the  
consideration that a small telescope may
 afford its possessor much pleasure of  
an intellectual and elevated character1 
even if he is never able by its means to
 effect original discoveries1 two       
arguments may be urged in favour of     
independent telescopic observation4 ,in 
the first place1 the student who wishes 
to appreciate the facts and theories of 
astronomy should familiarize himself    
with the nature of that instrument to   
which astronomers have been most largely
 indebted4 ,in the second place1 some of
 the most important discoveries in      
astronomy have been effected by means of
 telescopes of moderate power used      
skilfully and systematically4 ,one      
instance may suffice to show what can be
 done in this way4 ,the well-known      

telescopist ,goldschmidt 7who commenced 
astronomical observation at the age of  
forty-eight1 in #ahej7 added fourteen   
asteroids to the solar system1 not to   
speak of important discoveries of nebul 
and variable stars1 by means of a       
telescope only five feet in focal       
length1 mounted on a movable tripod     
stand4  ,the feeling experienced by     
those who look through a telescope for  
the first time1--especially if it is    
directed upon a planet or nebula--is    
commonly one of disappointment4 ,they   
have been told that such and such powers
 will exhibit ,jupiter's belts1         
,saturn's rings1 and the                
continent-outlines on ,mars2 yet1 though
 perhaps a higher power is applied1 they
 fail to detect these appearances1 and  
can hardly believe that they are        
perfectly distinct to the practised eye4
  ,the expectations of the beginner are 
especially liable to disappointment in  
one particular4 ,he forms an estimate of
 the view he is to obtain of a planet by

 multiplying the apparent diameter of   
the planet by the magnifying power of   
his telescope1 and comparing the result 
with the apparent diameter of the sun or
 moon4 ,let us suppose1 for instance1   
that on the day of observation          
,jupiter's apparent diameter is #de1 and
 that the telescopic power applied is   
#dj1 then in the telescope ,jupiter     
should appear to have a diameter of     
#ahjj1 or half a degree1 which is about 
the same as the moon's apparent         
diameter4 ,but when the observer looks  
through the telescope he obtains a      
view--interesting1 indeed1 and          
instructive--but very different from    
what the above calculation would lead   
him to expect4 ,he sees a disc          
apparently much smaller than the moon's1
 and not nearly so well-defined in      
outline2 in a line with the disc's      
centre there appear three or four minute
 dots of light1 the satellites of the   
planet2 and1 perhaps1 if the weather is 
favourable and the observer watchful1 he

 will be able to detect faint traces of 
belts across the planet's disc4  ,yet in
 such a case the telescope is not in    
fault4 ,the planet really appears of the
 estimated size4 ,in fact1 it is often  
possible to prove this in a very simple 
manner4 ,if the observer wait until the 
planet and the moon are pretty near     
together1 he will find that it is       
possible to view the planet with one eye
 through the telescope and the moon with
 the unaided eye1 in such a manner that 
the two discs may coincide1 and thus    
their relative apparent dimensions be at
 once recognised4 ,nor should the       
indistinctness and incompleteness of the
 view be attributed to imperfection of  
the telescope2 they are partly due to   
the nature of the observation and the   
low power employed1 and partly to the   
inexperience of the beginner4  ,it is to
 such a beginner that the following     
pages are specially addressed1 with the 
hope of affording him aid and           
encouragement in the use of one of the  

most enchanting of scientific           
instruments1--an instrument that has    
created for astronomers a new sense1 so 
to speak1 by which1 in the words of the 
ancient poet3      ,subjecere oculis    
distantia sidera nostris1       theraque
 ingenio supposuere suo4  ,in the first 
place1 it is necessary that the beginner
 should rightly know what is the nature 
of the instrument he is to use4 ,and    
this is the more necessary because1     
while it is perfectly easy to obtain    
such knowledge without any profound     
acquaintance with the science of optics1
 yet in many popular works on this      
subject the really important points are 
omitted1 and even in scientific works   
such points are too often left to be    
gathered from a formula4 ,when the      
observer has learnt what it is that his 
instrument is actually to do for him1 he
 will know how to estimate its          
performance1 and how to vary the        
application of its powers--whether      
illuminating or magnifying--according to

 the nature of the object to be         
observed4  ,let us consider what it is  
that limits the range of natural vision 
applied to distant objects4 ,what causes
 an object to become invisible as its   
distance increases8 ,two things are     
necessary that an object should be      
visible4 ,it must be large enough to be 
appreciated by the eye1 and it must send
 light enough4 ,thus increase of        
distance may render an object invisible1
 either through diminution of its       
apparent size1 or through diminution in 
the quantity of light it sends to the   
eye1 or through both these causes       
combined4 ,a telescope1 therefore1 or   
7as its name implies7 an instrument to  
render distant objects visible1 must be 
both a magnifying and an illuminating   
instrument4  ,illustration3 ,fig4 #a4   
,let ,,ef1 fig4 #a1 be an object1 not   
near to ,,ab as in the figure1 but so   
far off that the bounding lines from ,a 
and ,b would meet at the point          
corresponding to the point ,p4 ,then if 

a large convex glass ,,ab 7called an    
object-glass7 be interposed between the 
object and the eye1 all those rays      
which1 proceeding from ,p1 fall on ,,ab1
 will be caused to converge nearly to a 
point p4 ,the same is true for every    
point of the object ,,emf1 and thus a   
small image1 emf1 will be formed4 ,this 
image will not lie exactly on a flat    
surface1 but will be curved about the   
point midway between ,a and ,b as a     
centre4 ,now if the lens ,,ab is        
removed1 and an eye is placed at m to   
view the distant object ,,emf1 those    
rays only from each point of the object 
which fall on the pupil of the eye      
7whose diameter is about equal to mp    
suppose7 will serve to render the object
 visible4 ,on the other hand1 every     
point of the image emf has received the 
whole of the light gathered up by the   
large glass ,,ab4 ,if then we can only  
make this light available1 it is clear  
that we shall have acquired a large     
increase of light from the distant      

object4 ,now it will be noticed that the
 light which has converged to p1        
diverges from p so that an eye1 placed  
that this diverging pencil of rays may  
fall upon it1 would be too small to     
receive the whole of the pencil4 ,or1 if
 it did receive the whole of this       
pencil1 it clearly could not receive the
 whole of the pencils proceeding from   
other parts of the image emf4 ,something
 would be gained1 though1 even in this  
case1 since it is clear that an eye thus
 placed at a distance of ten inches from
 emf 7which is about the average        
distance of distinct vision7 would not  
only receive much more light from the   
image emf1 than it would from the object
 ,,emf1 but see the image much larger   
than the object4 ,it is in this way that
 a simple object-glass forms a          
telescope1 a circumstance we shall      
presently have to notice more at length4
 ,but we want to gain the full benefit  
of the light which has been gathered up 
for us by our object-glass4 ,we         

therefore interpose a small convex glass
 ab 7called an eye-glass7 between the   
image and the eye1 at such a distance   
from the image that the divergent pencil
 of rays is converted into a pencil of  
parallel or nearly parallel rays4 ,call 
this an emergent pencil4 ,then all the  
emergent pencils now converge to a point
 on the axial line m,m 7produced beyond 
m71 and an eye suitably placed can take 
in all of them at once4 ,thus the whole1
 or a large part1 of the image is seen  
at once4 ,but the image is seen inverted
 as shown4 ,this is the ,telescope1 as  
it was first discovered1 and such an    
arrangement would now be called a simple
 astronomical ,telescope4  ,let us      
clearly understand what each part of the
 astronomical telescope does for us3--  
,the object-glass ,,ab gives us an      
illuminated image1 the amount of        
illumination depending on the size of   
the object-glass4 ,the eye-glass enables
 us to examine the image                
microscopically4  ,we may apply         

eye-glasses of different focal length4  
,it is clear that the shorter the focal 
length of ab1 the nearer must ab be     
placed to the image1 and the smaller    
will the emergent pencils be1 but the   
greater the magnifying power of the     
eye-glass4 ,if the emergent pencils are 
severally larger than the pupil of the  
eye1 light is wasted at the expense of  
magnifying power4 ,therefore the        
eye-glass should never be of greater    
focal length than that which makes the  
emergent pencils about equal in diameter
 to the pupil of the eye4 ,on the other 
hand1 the eye-glass must not be of such 
small focal length that the image       
appears indistinct and contorted1 or    
dull for want of light4  ,illustration3 
,fig4 #b4  ,let us compare with the     
arrangement exhibited in fig4 #a that   
adopted by ,galileo4 ,surprise is       
sometimes expressed that this           
instrument1 which in the hands of the   
great ,florentine astronomer effected so
 much1 should now be known as the       

non-astronomical ,telescope4 ,i think   
this will be readily understood when we 
compare the two arrangements4  ,in the  
,galilean ,telescope a small concave    
eye-glass1 ab 7fig4 #b71 is placed      
between the object-glass and the image4 
,in fact1 no image is allowed to be     
formed in this arrangement1 but the     
convergent pencils are intercepted by   
the concave eye-glass1 and converted    
into parallel emergent pencils4 ,now in 
fig4 #b the concave eye-glass is so     
placed as to receive only a part of the 
convergent pencil ,a p ,b1 and this is  
the arrangement usually adopted4 ,by    
using a concave glass of shorter focus1 
which would therefore be placed nearer  
to m p1 the whole of the convergent     
pencil might be received in this as in  
the former case4 ,but then the axis of  
the emergent pencil1 instead of         
returning 7as we see it in fig4 #a7     
towards the axis of the telescope1 would
 depart as much from that axis4 ,thus   
there would be no point on the axis at  

which the eye could be so placed as to  
receive emergent pencils showing any    
considerable part of the object4 ,the   
difference may be compared to that      
between looking through the small end of
 a cone-shaped roll of paper and looking
 through the large end2 in the former   
case the eye sees at once all that is to
 be seen through the roll 7supposed     
fixed in position71 in the latter the   
eye may be moved about so as to command 
the same range of view1 but at any      
instant sees over a much smaller range4 
,to return to the arrangement actually  
employed1 which is illustrated by the   
common opera-glass4 ,we see that the    
full illuminating power of the telescope
 is not brought into play4 ,but this is 
not the only objection to the ,galilean 
,telescope4 ,it is obvious that if the  
part ,c ,d of the object-glass were     
covered1 the point ,p would not be      
visible1 whereas1 in the astronomical   
arrangement no other effect is produced 
on the visibility of an object1 by      

covering part of the object-glass1 than 
a small loss of illumination4 ,in other 
words1 the dimensions of the field of   
view of a ,galilean ,telescope depend on
 the size of the object-glass1 whereas  
in the astronomical ,telescope the field
 of view is independent of the size of  
the object-glass4 ,the difference may be
 readily tested4 ,if we direct an       
opera-glass upon any object1 we shall   
find that any covering placed over a    
part of the object-glass becomes visible
 when we look through the instrument1   
interfering therefore pro tanto with the
 range of view4 ,a covering similarly   
placed on any part of the object-glass  
of an astronomical telescope does not   
become visible when we look through the 
instrument4 ,the distinction has a very 
important bearing on the theory of      
telescopic vision4  ,in considering the 
application of the telescope to         
practical observation1 the circumstance 
that in the ,galilean ,telescope no real
 image is formed1 is yet more important4

 ,a real image admits of measurement1   
linear or angular1 while to a virtual   
image 7such an image1 for instance1 as  
is formed by a common looking-glass7 no 
such process can be applied4 ,in simple 
observation the only noticeable effect  
of this difference is that1 whereas in  
the astronomical ,telescope a stop or   
diaphragm can be inserted in the tube so
 as to cut off what is called the ragged
 edge of the field of view 7which       
includes all the part not reached by    
full pencils of light from the          
object-glass71 there is no means of     
remedying the corresponding defect in   
the ,galilean ,telescope4 ,it would be a
 very annoying defect in a telescope    
intended for astronomical observation1  
since in general the edge of the field  
of view is not perceptible at night4    
,the unpleasant nature of the defect may
 be seen by looking through an          
opera-glass1 and noticing the gradual   
fading away of light round the          
circumference of the field of view4     

,the properties of reflection as well as
 of refraction have been enlisted into  
the service of the astronomical         
observer4 ,the formation of an image by 
means of a concave mirror is exhibited  
in fig4 #c4 ,as the observer's head     
would be placed between the object and  
the mirror1 if the image1 formed as in  
fig4 #c1 were to be microscopically     
examined1 various devices are employed  
in the construction of reflecting       
telescopes to avoid the loss of light   
which would result--a loss which would  
be important even with the largest      
mirrors yet constructed4 ,thus1 in      
,gregory's ,telescope1 a small mirror1  
having its concavity towards the great  
one1 is placed in the axis of the tube  
and forms an image which is viewed      
through an aperture in the middle of the
 great mirror4 ,a similar plan is       
adopted in ,cassegrain's ,telescope1 a  
small convex mirror replacing the       
concave one4 ,in ,newton's ,telescope a 
small inclined-plane reflector is used1 

which sends the pencil of light off at  
right-angles to the axis of the tube4   
,in ,herschel's ,telescope the great    
mirror is inclined so that the image is 
formed at a slight distance from the    
axis of the telescope4 ,in the two first
 cases the object is viewed in the usual
 or direct way1 the image being erect in
 ,gregory's and inverted in             
,cassegrain's4 ,in the third the        
observer looks through the side of the  
telescope1 seeing an inverted image of  
the object4 ,in the last the observer   
sees the object inverted1 but not       
altered as respects right and left4 ,the
 last-mentioned method of viewing       
objects is the only one in which the    
observer's back is turned towards the   
object1 yet this method is called the   
front view--apparently quasi lucus a non
 lucendo4  ,illustration3 ,fig4 #c4  ,it
 appears1 then1 that in all astronomical
 ,telescopes1 reflecting or refracting1 
a real image of an object is submitted  
to microscopical examination4  ,of this 

fact the possessor of a telescope may   
easily assure himself2 for if the       
eye-glass be removed1 and a small screen
 be placed at the focus of the          
object-glass1 there will appear upon the
 screen a small picture of any object   
towards which the tube is turned4 ,but  
the image may be viewed in another way  
which requires to be noticed4 ,if the   
eye1 placed at a distance of five or six
 inches from the image1 be directed down
 the tube1 the image will be seen as    
before2 in fact1 just as a single convex
 lens of short focus is the simplest    
microscope1 so a simple convex lens of  
long focus is the simplest telescope4#a 
,but a singular circumstance will       
immediately attract the observer's      
notice4 ,a real picture1 or the image   
formed on the screen as in the former   
case1 can be viewed at varying          
distances2 but when we view the image   
directly1 it will be found that for     
distinct vision the eye must be placed  
almost exactly at a fixed distance from 

the image4 ,this peculiarity is more    
important than it might be thought at   
first sight4 ,in fact1 it is essential  
that the observer who would rightly     
apply the powers of his telescope1 or   
fairly test its performance1 should     
understand in what respect an image     
formed by an object-glass or            
object-mirror differs from a real       
object4  ,the peculiarities to be noted 
are the curvature1 indistinctness1 and  
false colouring of the image4  ,the     
curvature of the image is the least     
important of the three defects named--a 
fortunate circumstance1 since this      
defect admits neither of remedy nor     
modification4 ,the image of a distant   
object1 instead of lying in a plane1    
that is1 forming what is technically    
called a flat field1 forms part of a    
spherical surface whose centre is at the
 centre of the object-glass4 ,hence the 
centre of the field of view is somewhat 
nearer to the eye than are the outer    
parts of the field4 ,the amount of      

curvature clearly depends on the extent 
of the field of view1 and therefore is  
not great in powerful telescopes4 ,thus1
 if we suppose that the angular extent  
of the field is about half a degree 7a  
large or low-power field71 the centre is
 nearer than the boundary of the field  
by about #a-cbjth part only of the      
field's diameter4  ,the indistinctness  
of the image is partly due to the       
obliquity of the pencils which form     
parts of the image1 and partly to what  
is termed spherical aberration4 ,the    
first cause cannot be modified by the   
optician's skill1 and is not important  
when the field of view is small4        
,spherical aberration causes those parts
 of a pencil which fall near the        
boundary of a convex lens to converge to
 a nearer 7i4e4 shorter7 focus than     
those which fall near the centre4 ,this 
may be corrected by a proper selection  
of the forms of the two lenses which    
replace1 in all modern telescopes1 the  
single lens hitherto considered4  ,the  

false colouring of the image is due to  
chromatic aberration4 ,the pencil of    
light proceeding from a point1          
converges1 not to one point1 but to a   
short line of varying colour4 ,thus a   
series of coloured images is formed1 at 
different distances from the            
object-glass4 ,so that1 if a screen were
 placed to receive the mean image in    
focus1 a coloured fringe due to the     
other images 7out of focus1 and         
therefore too large7 would surround the 
mean image4  ,newton supposed that it   
was impossible to get rid of this       
defect1 and therefore turned his        
attention to the construction of        
reflectors4 ,but the discovery that the 
dispersive powers of different glasses  
are not proportional to their reflective
 powers1 supplied opticians with the    
means of remedying the defect4 ,let us  
clearly understand what is the discovery
 referred to4 ,if with a glass prism of 
a certain form we produce a spectrum of 
the sun1 this spectrum will be thrown a 

certain distance away from the point on 
which the sun's rays would fall if not  
interfered with4 ,this distance depends 
on the refractive power of the glass4   
,the spectrum will have a certain       
length1 depending on the dispersive     
power of the glass4 ,now1 if we change  
our prism for another of exactly the    
same shape1 but made of a different kind
 of glass1 we shall find the spectrum   
thrown to a different spot4 ,if it      
appeared that the length of the new     
spectrum was increased or diminished in 
exactly the same proportion as its      
distance from the line of the sun's     
direct light1 it would have been        
hopeless to attempt to remedy chromatic 
aberration4 ,newton took it for granted 
that this was so4 ,but the experiments  
of ,hall and the ,dollonds showed that  
there is no such strict proportionality 
between the dispersive and refractive   
powers of different kinds of glass4 ,it 
accordingly becomes possible to correct 
the chromatic aberration of one glass by

 superadding that of another4           
,illustration3 ,fig4 #d4  ,this is      
effected by combining1 as shown in fig4 
#d1 a convex lens of crown glass with a 
concave lens of flint glass1 the convex 
lens being placed nearest to the object4
 ,a little colour still remains1 but not
 enough to interfere seriously with the 
distinctness of the image4  ,but even if
 the image formed by the object-glass   
were perfect1 yet this image1 viewed    
through a single convex lens of short   
focus placed as in fig4 #a1 would appear
 curved1 indistinct1 coloured1 and also 
distorted1 because viewed by pencils of 
light which do not pass through the     
centre of the eye-glass4 ,these effects 
can be diminished 7but not entirely     
removed together7 by using an eye-piece 
consisting of two lenses instead of a   
single eye-glass4 ,the two forms of     
eye-piece most commonly employed are    
exhibited in figs4 #e and #f4 ,fig4 #e  
is ,huyghens' eye-piece1 called also the
 negative eye-piece1 because a real     

image is formed behind the field-glass  
7the lens which lies nearest to the     
object-glass74 ,fig4 #f represents      
,ramsden's eye-piece1 called also the   
positive eye-piece1 because the real    
image formed by the object-glass lies in
 front of the field-glass4              
,illustration3 ,fig4 #e4  ,illustration3
 ,fig4 #f4  ,the course of a slightly   
oblique pencil through either eye-piece 
is exhibited in the figures4 ,the lenses
 are usually plano-convex1 the          
convexities being turned towards the    
object-glass in the negative eye-piece1 
and towards each other in the positive  
eye-piece4 ,coddington has shown1       
however1 that the best forms for the    
lenses of the negative eye-piece are    
those shown in fig4 #e4  ,the negative  
eye-piece1 being achromatic1 is commonly
 employed in all observations requiring 
distinct vision only4 ,but as it is     
clearly unfit for observations requiring
 micrometrical measurement1 or reference
 to fixed lines at the focus of the     

object-glass1 the positive eye-piece is 
used for these purposes4  ,for observing
 objects at great elevations the        
diagonal eye-tube is often convenient4  
,its construction is shown in fig4 #g4  
,,abc is a totally reflecting prism of  
glass4 ,the rays from the object-glass  
fall on the face ,,ab1 are totally      
reflected on the face ,,bc1 and emerge  
through the face ,,ac4 ,in using this   
eye-piece1 it must be remembered that it
 lengthens the sliding eye-tube1 which  
must therefore be thrust further in1 or 
the object will not be seen in focus4   
,there is an arrangement by which the   
change of direction is made to take     
place between the two glasses of the    
eye-piece4 ,with this arrangement 7known
 as the diagonal eye-piece7 no          
adjustment of the eye-tube is required4 
,however1 for amateurs' telescopes the  
more convenient arrangement is the      
diagonal eye-tube1 since it enables the 
observer to apply any eye-piece he      
chooses1 just as with the simple sliding

 eye-tube4  ,illustration3 ,fig4 #g4    
,we come next to the important question 
of the mounting of our telescope4  ,the 
best known1 and1 in some respects1 the  
simplest method of mounting a telescope 
for general observation is that known as
 the altitude-and-azimuth mounting4 ,in 
this method the telescope is pointed    
towards an object by two motions1--one  
giving the tube the required altitude   
7or elevation71 the other giving it the 
required azimuth 7or direction as       
respects the compass points74  ,for     
small alt-azimuths the ordinary         
pillar-and-claw stand is sufficiently   
steady4 ,for larger instruments other   
arrangements are needed1 both to give   
the telescope steadiness1 and to supply 
slow movements in altitude and azimuth4 
,the student will find no difficulty in 
understanding the arrangement of        
sliding-tubes and rack-work commonly    
adopted4 ,this arrangement seems to me  
to be in many respects defective1       
however4 ,the slow movement in altitude 

is not uniform1 but varies in effect    
according to the elevation of the object
 observed4 ,it is also limited in range2
 and quite a little series of operations
 has to be gone through when it is      
required to direct the telescope towards
 a new quarter of the heavens4 ,however 
expert the observer may become by       
practice in effecting these operations1 
they necessarily take up some time      
7performed as they must be in the dark1 
or by the light of a small lantern71 and
 during this time it often happens that 
a favourable opportunity for observation
 is lost4  ,these disadvantages are     
obviated when the telescope is mounted  
in such a manner as is exhibited in fig4
 #h1 which represents a telescope of my 
own construction4 ,the slow movement in 
altitude is given by rotating the rod   
he1 the endless screw in which turns the
 small wheel at b1 whose axle in turn   
bears a pinion-wheel working in the     
teeth of the quadrant a4 ,the slow      
movement in azimuth is given in like    

manner by rotating the rod h'e'1 the    
lantern-wheel at the end of which turns 
a crown-wheel on whose axle is a        
pinion-wheel working in the teeth of the
 circle c4 ,the casings at e and e'1 in 
which the rods he and h'e' respectively 
work1 are so fastened by elastic cords  
that an upward pressure on the handle h1
 or a downward pressure on the handle   
h'1 at once releases the endless screw  
or the crown-wheel respectively1 so that
 the telescope can be swept at once     
through any desired angle in altitude or
 azimuth4 ,this method of mounting has  
other advantages2 the handles are       
conveniently situated and constant in   
position2 also1 as they do not work     
directly on the telescope1 they can be  
turned without setting the tube in      
vibration4  ,illustration3 ,fig4 #h4  ,i
 do not recommend the mounting to be    
exactly as shown in fig4 #h4 ,that      
method is much too expensive for an     
alt-azimuth4 ,but a simple arrangement  
of belted wheels in place of the toothed

 wheels a and c might very readily be   
prepared by the ingenious amateur       
telescopist2 and ,i feel certain that   
the comfort and convenience of the      
arrangement would amply repay him for   
the labour it would cost him4 ,my own   
telescope--though the large             
toothed-wheel and the quadrant were made
 inconveniently heavy 7through a mistake
 of the workman who constructed the     
instrument7--worked as easily and almost
 as conveniently as an equatorial4      
,still1 it is well for the observer who 
wishes systematically to survey the     
heavens--and who can afford the         
expense--to obtain a well-mounted       
equatorial4 ,in this method of mounting1
 the main axis is directed to the pole  
of the heavens2 the other axis1 at right
 angles to the first1 carries the       
telescope-tube4 ,one of the many methods
 adopted for mounting equatorials is    
that exhibited--with the omission of    
some minor details--in fig4 #i4 a is the
 polar axis1 b is the axis 7called the  

declination axis7 which bears the       
telescope4 ,the circles c and d serve to
 indicate1 by means of verniers         
revolving with the axes1 the motion of  
the telescope in right ascension and    
declination1 respectively4 ,the weight w
 serves to counterpoise the telescope1  
and the screws s1 s1 s1 s1 serve to     
adjust the instrument so that the polar 
axis shall be in its proper position4   
,the advantage gained by the equatorial 
method of mounting is that only one     
motion is required to follow a star4    
,owing to the diurnal rotation of the   
earth1 the stars appear to move         
uniformly in circles parallel to the    
celestial equator2 and it is clear that 
a star so moving will be kept in the    
field of view1 if the telescope1 once   
directed to the star1 be made to revolve
 uniformly and at a proper rate round   
the polar axis4  ,illustration3 ,fig4   
#i4  ,the equatorial can be directed by 
means of the circles c and d to any     
celestial object whose right ascension  

and declination are known4 ,on the other
 hand1 to bring an object into the field
 of view of an alt-azimuth1 it is       
necessary1 either that the object itself
 should be visible to the naked eye1 or 
else that the position of the object    
should be pretty accurately learned from
 star-maps1 so that it may be picked up 
by the alt-azimuth after a little       
searching4 ,a small telescope called a  
finder is usually attached to all       
powerful telescopes intended for general
 observation4 ,the finder has a large   
field of view1 and is adjusted so as to 
have its axis parallel to that of the   
large telescope4 ,thus a star brought to
 the centre of the large field of the   
finder 7indicated by the intersection of
 two lines placed at the focus of the   
eye-glass7 is at1 or very near1 the     
centre of the small field of the large  
telescope4  ,if a telescope has no      
finder1 it will be easy for the student 
to construct one for himself1 and will  
be a useful exercise in optics4 ,two    

convex lenses not very different in size
 from those shown in fig4 #a1 and placed
 as there shown--the distance between   
them being the sum of the focal lengths 
of the two glasses--in a small tube of  
card1 wood1 or tin1 will serve the      
purpose of a finder for a small         
telescope4 ,it can be attached by wires 
to the telescope-tube1 and adjusted each
 night before commencing observation4   
,the adjustment is thus managed3--a low 
power being applied to the telescope1   
the tube is turned towards a bright     
star2 this is easily effected with a low
 power2 then the finder is to be fixed1 
by means of its wires1 in such a        
position that the star shall be in the  
centre of the field of the finder when  
also in the centre of the telescope's   
field4 ,when this has been done1 the    
finder will greatly help the            
observations of the evening2 since with 
high powers much time would be wasted in
 bringing an object into the field of   
view of the telescope without the aid of

 a finder4 ,yet more time would be      
wasted in the case of an object not     
visible to the naked eye1 but whose     
position with reference to several      
visible stars is known2 since1 while it 
is easy to bring the point required to  
the centre of the finder's field1 in    
which the guiding stars are visible1 it 
is very difficult to direct the         
telescope's tube on a point of this     
sort4 ,a card tube with wire fastenings1
 such as we have described1 may appear a
 very insignificant contrivance to the  
regular observer1 with his well-mounted 
equatorial and carefully-adjusted       
finder4 ,but to the first attempts of   
the amateur observer it affords no      
insignificant assistance1 as ,i can aver
 from my own experience4 ,without it--a 
superior finder being wanting--our      
half-hours would soon be wasted away in 
that most wearisome and annoying of all 
employments1 trying to pick up celestial
 objects4  ,it behoves me at this point 
to speak of star-maps4 ,such maps are of

 many different kinds4 ,there are the   
,observatory maps1 in which the places  
of thousands of stars are recorded with 
an amazing accuracy4 ,our beginner is   
not likely to make use of1 or to want1  
such maps as these4 ,then there are maps
 merely intended to give a good general 
idea of the appearance of the heavens at
 different hours and seasons4 ,plate ,i4
 presents four maps of this sort2 but a 
more complete series of eight maps has  
been published by ,messrs4 ,walton and  
,maberly in an octavo work2 and my own  
',constellation-,seasons' give1 at the  
same price1 twelve quarto maps 7of four 
of which those in ,plate ,i4 are        
miniatures71 showing the appearance of  
the sky at any hour from month to month1
 or on any night1 at successive         
intervals of two hours4 ,but maps       
intermediate in character to these and  
to ,observatory maps are required by the
 amateur observer4 ,such are the        
,society's six gnomonic maps1 the set of
 six gnomonic maps in ,johnstone's      

',atlas of ,astronomy1' and my own set  
of twelve gnomonic maps4 ,the ,society's
 maps are a remarkably good set1        
containing on the scale of a ten-inch   
globe all the stars in the ,catalogue of
 the ,astronomical ,society 7down to the
 fifth magnitude74 ,the distortion1     
however1 is necessarily enormous when   
the celestial sphere is presented in    
only six gnomonic maps4 ,in my maps all 
the stars of the ,british ,association  
,catalogue down to the fifth magnitude  
are included on the scale of a six-inch 
globe4 ,the distortion is scarcely a    
fourth of that in the ,society's maps4  
,the maps are so arranged that the      
relative positions of all the stars in  
each hemisphere can be readily gathered 
from a single view2 and black           
duplicate-maps serve to show the        
appearance of the constellations4  ,it  
is often convenient to make small maps  
of a part of the heavens we may wish to 
study closely4 ,my ',handbook of the    
,stars' has been prepared to aid the    

student in the construction of such     
maps4  ,in selecting maps it is well to 
be able to recognise the amount of      
distortion and scale-variation4 ,this   
may be done by examining the spaces     
included between successive parallels   
and meridians1 near the edges and angles
 of the maps1 and comparing these either
 with those in the centre of the map1 or
 with the known figures and dimensions  
of the corresponding spaces on a globe4 
,we may now proceed to discuss the      
different tests which the intending     
purchaser of a telescope should apply to
 the instrument4  ,the excellence of an 
object-glass can be satisfactorily      
determined only by testing the          
performance of the telescope in the     
manner presently to be described4 ,but  
it is well to examine the quality of the
 glass as respects transparency and     
uniformity of texture4 ,bubbles1        
scratches1 and other such defects1 are  
not very important1 since they do not   
affect the distinctness of the field as 

they would in a ,galilean ,telescope1--a
 little light is lost1 and that is all4 
,the same remark applies to dust upon   
the glass4 ,the glass should be kept as 
free as possible from dirt1 damp1 or    
dust1 but it is not advisable to remove 
every speck which1 despite such         
precaution1 may accidentally fall upon  
the object-glass4 ,when it becomes      
necessary to clean the glass1 it is to  
be noted that the substance used should 
be soft1 perfectly dry1 and free from   
dust4 ,silk is often recommended1 but   
some silk is exceedingly objectionable  
in texture1--old silk1 perfectly soft to
 the touch1 is perhaps as good as       
anything4 ,if the dust which has fallen 
on the glass is at all gritty1 the glass
 will suffer by the method of cleaning  
commonly adopted1 in which the dust is  
gathered up by pressure4 ,the proper    
method is to clean a small space near   
the edge of the glass1 and to sweep from
 that space as centre4 ,in this way the 
dust is pushed before the silk or       

wash-leather1 and does not cut the      
glass4 ,it is well always to suspect the
 presence of gritty dust1 and adopt this
 cautious method of cleaning4  ,the two 
glasses should on no account be         
separated4  ,in examining an eye-piece1 
the quality of the glass should be      
noted1 and care taken that both glasses 
7but especially the field-glass7 are    
free from the least speck1 scratch1 or  
blemish of any kind1 for these defects  
will be exhibited in a magnified state  
in the field of view4 ,hence the        
eye-pieces require to be as carefully   
preserved from damp and dust as the     
object-glass1 and to be more frequently 
cleaned4  ,the tube of the telescope    
should be light1 but strong1 and free   
from vibration4 ,its quality in the last
 respect can be tested by lightly       
striking it when mounted2 the sound     
given out should be dead or             
non-resonant4 ,the inside of the tube   
must absorb extraneous light1 and should
 therefore be coloured a dull black2 and

 stops of varying radius should be      
placed along its length with the same   
object4 ,sliding tubes1 rack-work1 etc41
 should work closely1 yet easily4  ,the 
telescope should be well balanced for   
vision with the small astronomical      
eye-pieces4 ,but as there is often      
occasion to use appliances which disturb
 the balance1 it is well to have the    
means of at once restoring equilibrium4 
,a cord ring running round the tube     
7pretty tightly1 so as to rest still    
when the tube is inclined71 and bearing 
a small weight1 will be all that is     
required for this purpose2 it must be   
slipped along the tube until the tube is
 found to be perfectly balanced4        
,nothing is more annoying than1 after   
getting a star well in the field1 to see
 the tube shift its position through    
defective balance1 and thus to have to  
search again for the star4 ,even with   
such an arrangement as is shown in fig4 
#h1 though the tube cannot readily shift
 its position1 it is better to have it  

well balanced4  ,the quality of the     
stand has a very important influence on 
the performance of a telescope4 ,in     
fact1 a moderately good telescope1      
mounted on a steady stand1 working      
easily and conveniently1 will not only  
enable the observer to pass his time    
much more pleasantly1 but will          
absolutely exhibit more difficult       
objects than a finer instrument on a    
rickety1 ill-arranged stand4 ,a good    
observing-chair is also a matter of some
 importance1 the least constraint or    
awkwardness of position detracting      
considerably from the power of distinct 
vision4 ,such1 at least1 is my own      
experience4  ,but the mere examination  
of the glasses1 tube1 mounting1 c41 is  
only the first step in the series of    
tests which should be applied to a      
telescope1 since the excellence of the  
instrument depends1 not on its size1 the
 beauty of its mounting1 or any         
extraneous circumstances1 but on its    
performance4  ,the observer should first

 determine whether the chromatic        
aberration is corrected4 ,to ascertain  
this the telescope should be directed to
 the moon1 or 7better7 to ,jupiter1 and 
accurately focussed for distinct vision4
 ,if1 then1 on moving the eye-piece     
towards the object-glass1 a ring of     
purple appears round the margin of the  
object1 and on moving the eye-glass in  
the contrary direction a ring of green1 
the chromatic aberration is corrected1  
since these are the colours of the      
secondary spectrum4  ,to determine      
whether the spherical aberration is     
corrected1 the telescope should be      
directed towards a star of the third or 
fourth magnitude1 and focussed for      
distinct vision4 ,a cap with an aperture
 of about one-half its diameter should  
then be placed over the object-glass4   
,if no new adjustment is required for   
distinct vision1 the spherical          
aberration is corrected1 since the mean 
focal length and the focal length of the
 central rays are equal4 ,if1 when the  

cap is on1 the eye-piece has to be      
pulled out for distinct vision1 the     
spherical aberration has not been fully 
corrected2 if the eye-piece has to be   
pushed in1 the aberration has been      
over-corrected4 ,as a further test1 we  
may cut off the central rays1 by means  
of a circular card covering the middle  
of the object-glass1 and compare the    
focal length for distinct vision with   
the focal length when the cap is        
applied4 ,the extent of the spherical   
aberration may be thus determined2 but  
if the first experiment gives a         
satisfactory result1 no other is        
required4  ,a star of the first         
magnitude should next be brought into   
the field of view4 ,if an irradiation   
from one side is perceived1 part of the 
object-glass has not the same refractive
 power as the rest2 and the part which  
is defective can be determined by       
applying in different positions a cap   
which hides half the object-glass4 ,if  
the irradiation is double1 it will      

probably be found that the object-glass 
has been too tightly screwed1 and the   
defect will disappear when the glass is 
freed from such undue pressure4  ,if the
 object-glass is not quite at right     
angles to the axis of the tube1 or if   
the eye-tube is at all inclined1 a like 
irradiation will appear when a bright   
star is in the field4 ,the former defect
 is not easily detected or remedied2 nor
 is it commonly met with in the work of 
a careful optician4 ,the latter defect  
may be detected by cutting out three    
circular cards of suitable size with a  
small aperture at the centre of each1   
and inserting one at each end of the    
eye-tube1 and one over the object-glass4
 ,if the tube is rightly placed the     
apertures will of course lie in a right 
line1 so that it will be possible to    
look through all three at once4 ,if not1
 it will be easy to determine towards   
what part of the object-glass the       
eye-tube is directed1 and to correct the
 position of the tube accordingly4  ,the

 best tests for determining the defining
 power of a telescope are close double  
or multiple stars1 the components of    
which are not very unequal4 ,the        
illuminating power should be tested by  
directing the telescope towards double  
or multiple stars having one or more    
minute components4 ,many of the nebul   
serve as tests both for illumination and
 defining power4 ,as we proceed we shall
 meet with proper objects for testing   
different telescopes4 ,for the present1 
let the following list suffice4 ,it is  
selected from ,admiral ,smyth's tests1  
obtained by diminishing the aperture of 
a #f-;in4 telescope having a focal      
length of #h-a_/b feet3  ,a two-inch    
aperture1 with powers of from #fj to    
#ajj1 should exhibit  alpha ,piscium    
7#ce74    delta ,cassiopei 7#ie71       
mag4 7#d and #g-a_/b7 gamma ,leonis     
7#cb74    ,polaris 7#ahf71 mag4 7#b-a_/b
                               and      
#i-a_/b7  ,a four-inch1 powers #hj to   
#abj1 should exhibit  xi ,urs ,majoris  

7#bd74  sigma ,cassiopei 7#ca71         
mag4 7#f and #h74 gamma ,ceti 7#bf74    
delta ,geminorum 7#ga71                 
mag4 7#d and #i74  ,the tests in the    
first column are for definition1 those  
in the second for illumination4 ,it will
 be noticed that1 though in the case of 
,polaris the smaller aperture may be    
expected to show the small star of less 
than the #ith magnitude1 a larger       
aperture is required to show the #hth   
magnitude component of sigma ,cassiopei1
 on account of the greater closeness of 
this double4  ,in favourable weather the
 following is a good general test of the
 performance of a telescope3--,a star of
 the #crd or #dth magnitude at a        
considerable elevation above the horizon
 should exhibit a small well defined    
disc1 surrounded by two or three fine   
rings of light4  ,a telescope should not
 be mounted within doors1 if it can be  
conveniently erected on solid ground1 as
 every movement in the house will cause 
the instrument to vibrate unpleasantly4 

,further1 if the telescope is placed in 
a warm room1 currents of cold air from  
without will render observed objects    
hazy and indistinct4 ,in fact1 ,sir ,w4 
,herschel considered that a telescope   
should not even be erected near a house 
or elevation of any kind round which    
currents of air are likely to be        
produced4 ,if a telescope is used in a  
room1 the temperature of the room should
 be made as nearly equal as possible to 
that of the outer air4  ,when a         
telescope is used out of doors a        
'dew-cap1' that is1 a tube of tin or    
pasteboard1 some ten or twelve inches   
long1 should be placed on the end of the
 instrument1 so as to project beyond the
 object-glass4 ,for glass is a good     
radiator of heat1 so that dew falls     
heavily upon it1 unless the radiation is
 in some way checked4 ,the dew-cap does 
this effectually4 ,it should be         
blackened within1 especially if made of 
metal4 ,after use1 says old ,kitchener1 
the telescope should be kept in a warm  

place long enough for any moisture on   
the object-glass to evaporate4 ,if damp 
gets between the glasses it produces a  
fog 7which opticians call a sweat7 or   
even a seaweed-like vegetation1 by which
 a valuable glass may be completely     
ruined4  ,the observer should not leave 
to the precious hours of the night the  
study of the bearing and position of the
 objects he proposes to examine4 ,this  
should be done by day--an arrangement   
which has a twofold advantage1--the time
 available for observation is           
lengthened1 and the eyes are spared     
sudden changes from darkness to light1  
and vice vers4 ,besides1 the eye is     
ill-fitted to examine difficult objects1
 after searching by candle-light amongst
 the minute details recorded in maps or 
globes4 ,of the effect of rest to the   
eye we have an instance in ,sir ,j4     
,herschel's rediscovery of the          
satellites of ,uranus1 which he effected
 after keeping his eyes in darkness for 
a quarter of an hour4 ,kitchener1       

indeed1 goes so far as to recommend     
7with a crede experto7 an interval of   
sleep in the darkness of the            
observing-room before commencing        
operations4 ,i have never tried the     
experiment1 but ,i should expect it to  
have a bad rather than a good effect on 
the eyesight1 as one commonly sees the  
eyes of a person who has been sleeping  
in his day-clothes look heavy and       
bloodshot4  ,the object or the part of  
an object to be observed should be      
brought as nearly as possible to the    
centre of the field of view4 ,when there
 is no apparatus for keeping the        
telescope pointed upon an object1 the   
best plan is so to direct the telescope 
by means of the finder1 that the object 
shall be just out of the field of view1 
and be brought 7by the earth's motion7  
across the centre of the field4 ,thus   
the vibrations which always follow the  
adjustment of the tube will have        
subsided before the object appears4 ,the
 object should then be intently watched 

during the whole interval of its passage
 across the field of view4  ,it is      
important that the student should       
recognise the fact that the highest     
powers do not necessarily give the best 
views of celestial objects4 ,high powers
 in all cases increase the difficulty of
 observation1 since they diminish the   
field of view and the illumination of   
the object1 increase the motion with    
which 7owing to the earth's motion7 the 
image moves across the field1 and       
magnify all defects due to instability  
of the stand1 imperfection of the       
object-glass1 or undulation of the      
atmosphere4 ,a good object-glass of     
three inches aperture will in very      
favourable weather bear a power of about
 #cjj1 when applied to the observation  
of close double or multiple stars1 but  
for all other observations much lower   
powers should be used4 ,nothing but     
failure and annoyance can follow the    
attempt to employ the highest powers on 
unsuitable objects or in unfavourable   

weather4  ,the greatest care should be  
taken in focussing the telescope4 ,when 
high powers are used this is a matter of
 some delicacy4 ,it would be well if the
 eye-pieces intended for a telescope    
were so constructed that when the       
telescope is focussed for one1 this     
might be replaced by any other without  
necessitating any use of the focussing  
rack-work4 ,this could be readily       
effected by suitably placing the        
shoulder which limits the insertion of  
the eye-piece4  ,it will be found that1 
even in the worst weather for           
observation1 there are instants of      
distinct vision 7with moderate powers7  
during which the careful observer may   
catch sight of important details2 and1  
similarly1 in the best observing        
weather1 there are moments of unusually 
distinct vision well worth patient      
waiting for1 since in such weather alone
 the full powers of the telescope can be
 employed4  ,the telescopist should not 
be deterred from observation by the     

presence of fog or haze1 since with a   
hazy sky definition is often singularly 
good4  ,the observer must not expect    
distinct vision of objects near the     
horizon4 ,objects near the eastern      
horizon during the time of morning      
twilight are especially confused by     
atmospheric undulations2 in fact1 early 
morning is a very unfavourable time for 
the observation of all objects4  ,the   
same rules which we have been applying  
to refractors1 serve for reflectors4    
,the performance of a reflector will be 
found to differ in some respects1       
however1 from that of a refractor4 ,mr4 
,dawes is1 we believe1 now engaged in   
testing reflectors1 and his unequalled  
experience of refractors will enable him
 to pronounce decisively on the relative
 merits of the two classes of           
telescopes4  ,we have little to say     
respecting the construction of          
telescopes4 ,whether it is advisable or 
not for an amateur observer to attempt  
the construction of his own telescope is

 a question depending entirely on his   
mechanical ability and ingenuity4 ,my   
own experience of telescope construction
 is confined to the conversion of a     
#c-;feet into a #e-a_/b-;feet telescope4
 ,this operation involved some          
difficulties1 since the aperture had to 
be increased by about an inch4 ,i found 
a tubing made of alternate layers of    
card and calico well pasted together1 to
 be both light and strong4 ,but for the 
full length of tube ,i think a core of  
metal is wanted4 ,a learned and         
ingenious friend1 ,mr4 ,sharp1 ,fellow  
of ,st4 ,john's ,college1 informs me    
that a tube of tin1 covered with layers 
of brown paper1 well pasted and thicker 
near the middle of the tube1 forms a    
light and strong telescope-tube1 almost 
wholly free from vibration4  ,suffer no 
inexperienced person to deal with your  
object-glass4 ,i knew a valuable glass  
ruined by the proceedings of a workman  
who had been told to attach three pieces
 of brass round the cell of the double  

lens4 ,what he had done remained        
unknown1 but ever after a wretched glare
 of light surrounded all objects of any 
brilliancy4  ,one word about the        
inversion of objects by the astronomical
 telescope4 ,it is singular that any    
difficulty should be felt about so      
simple a matter1 yet ,i have seen in the
 writings of more than one distinguished
 astronomer1 wholly incorrect views as  
to the nature of the inversion4 ,one    
tells us that to obtain the correct     
presentation from a picture taken with a
 telescope1 the view should be inverted1
 held up to the light1 and looked at    
from the back of the paper4 ,another    
tells us to invert the picture and hold 
it opposite a looking-glass4 ,neither   
method is correct4 ,the simple          
correction wanted is to hold the picture
 upside down--the same change which     
brings the top to the bottom brings the 
right to the left1 i4e41 fully corrects 
the inversion4  ,in the case1 however1  
of a picture taken by an ,herschelian   

reflector1 the inversion not being      
complete1 a different method must be    
adopted4 ,in fact1 either of the        
above-named processes1 incorrect for the
 ordinary astronomical1 would be correct
 for the ,herschelian ,telescope4 ,the  
latter inverts but does not reverse     
right and left2 therefore after         
inverting our picture we must           
interchange right and left because they 
have been reversed by the inversion4    
,this is effected either by looking at  
the picture from behind1 or by holding  
it up to a mirror4  ,illustration3      
,,plate ,,ii4     ,,chapter ,,ii4  ,a   
,,half-,,hour ,,with ,,orion1 ,,lepus   
,,taurus1 ,,etc4   ,any of the          
half-hours here assigned to the         
constellation-seasons may be taken      
first1 and the rest in seasonal or      
cyclic order4 ,the following            
introductory remarks are applicable to  
each3--  ,if we stand on an open space1 
on any clear night1 we see above us the 
celestial dome spangled with stars1     

apparently fixed in position4 ,but after
 a little time it becomes clear that    
these orbs are slowly shifting their    
position4 ,those near the eastern       
horizon are rising1 those near the      
western setting4 ,careful and continuous
 observation would show that the stars  
are all moving in the same way1         
precisely1 as they would if they were   
fixed to the concave surface of a vast  
hollow sphere1 and this sphere rotated  
about an axis4 ,this axis1 in our       
latitude1 is inclined about #ea-a_/b to 
the horizon4 ,of course only one end of 
this imaginary axis can be above our    
horizon4 ,this end lies very near a star
 which it will be well for us to become 
acquainted with at the beginning of our 
operations4 ,it lies almost exactly     
towards the north1 and is raised from   
#ej to #ec 7according to the season and 
hour7 above the horizon4 ,there is an   
easy method of finding it4  ,we must    
first find the ,greater ,bear4 ,it will 
be seen from ,plate #a1 that on a spring

 evening the seven conspicuous stars of 
this constellation are to be looked for 
towards the north-east1 about half way  
between the horizon and the point       
overhead 7or zenith71 the length of the 
set of stars being vertical4 ,on a      
summer's evening the ,great ,bear is    
nearly overhead4 ,on an autumn evening  
he is towards the north-west1 the length
 of the set of seven being somewhat     
inclined to the horizon4 ,finally1 on a 
winter's evening1 he is low down towards
 the north1 the length of the set of    
seven stars being nearly in a horizontal
 direction4  ,having found the seven    
stars1 we make use of the pointers alpha
 and beta 7shown in ,plate #a7 to       
indicate the place of the ,pole-star1   
whose distance from the pointer alpha is
 rather more than three times the       
distance of alpha from beta4  ,now stand
 facing the ,pole-star4 ,then all the   
stars are travelling round that star in 
a direction contrary to that in which   
the hands of a watch move4 ,thus the    

stars below the pole are moving towards 
the right1 those above the pole towards 
the left1 those to the right of the pole
 upwards1 those to the left of the pole 
downwards4  ,next face the south4 ,then 
all the stars on our left1 that is1     
towards the east1 are rising slantingly 
towards the south2 those due south are  
moving horizontally to the right1 that  
is1 towards the west2 and those on our  
right are passing slantingly downwards  
towards the west4  ,it is important to  
familiarise ourselves with these        
motions1 because it is through them that
 objects pass out of the field of view  
of the telescope1 and by moving the tube
 in a proper direction we can easily    
pick up an object that has thus passed  
away1 whereas if we are not familiar    
with the varying motions in different   
parts of the celestial sphere1 we may   
fail in the attempt to immediately      
recover an object1 and waste time in the
 search for it4  ,the consideration of  
the celestial motions shows how         

advantageous it is1 when using an       
alt-azimuth1 to observe objects as      
nearly as possible due south4 ,of course
 in many cases this is impracticable1   
because a phenomenon we wish to watch   
may occur when an object is not situated
 near the meridian4 ,but in examining   
double stars there is in general no     
reason for selecting objects            
inconveniently situated4 ,we can wait   
till they come round to the meridian1   
and then observe them more comfortably4 
,besides1 most objects are higher1 and  
therefore better seen1 when due south4  
,northern objects1 and especially those 
within the circle of perpetual          
apparition1 often culminate 7that is1   
cross the meridian1 or north and south  
line7 at too great a height for         
comfortable vision4 ,in this case we    
should observe them towards the east or 
west1 and remember that in the first    
case they are rising1 and in the latter 
they are setting1 and that in both cases
 they have also a motion from left to   

right4  ,if we allow an object to pass  
right across the field of view 7the     
telescope being fixed71 the apparent    
direction of its motion is the exact    
reverse of the true direction of the    
star's motion4 ,this will serve as a    
guide in shifting the alt-azimuth after 
a star has passed out of the field of   
view4  ,the following technical terms   
must be explained4 ,that part of the    
field of view towards which the star    
appears to move is called the preceding 
part of the field1 the opposite being   
termed the following part4 ,the motion  
for all stars1 except those lying in an 
oval space extending from the zenith to 
the pole of the heavens1 is more or less
 from right to left 7in the inverted    
field74 ,now1 if we suppose a star to   
move along a diameter of the field so as
 to divide the field into two           
semicircles1 then in all cases in which 
this motion takes places from right to  
left1 that semicircle which contains the
 lowest point 7apparently7 of the field 

is the northern half1 the other is the  
southern half4 ,over the oval space just
 mentioned the reverse holds4  ,thus the
 field is divided into four quadrants1  
and these are termed north following    
7n4f47 and south following 7s4f472 north
 preceding 7n4p471 and south preceding  
7s4p474 ,the student can have no        
difficulty in interpreting these terms1 
since he knows which is the following   
and which the preceding semicircle1     
which the northern and which the        
southern4 ,in the figures of plates #c  
and #e1 the letters n4f41 n4p41 c41 are 
affixed to the proper quadrants4 ,it is 
to be remembered that the quadrants thus
 indicated are measured either way from 
the point and feather of the diametral  
arrows4  ,next1 of the apparent annual  
motion of the stars4 ,this takes place  
in exactly the same manner as the daily 
motion4 ,if we view the sky at eight    
o'clock on any day1 and again at the    
same hour one month later1 we shall find
 that at the latter observation 7as     

compared with the former7 the heavens   
appear to have rotated by the twelfth   
part of a complete circumference1 and   
the appearance presented is precisely   
the same as we should have observed had 
we waited for two hours 7the twelfth    
part of a day7 on the day of the first  
observation4         99       99        
99       99       99  ,our survey of the
 heavens is supposed to be commenced    
during the first quarter of the year1 at
 ten o'clock on the #bjth of ,january1  
or at nine on the #eth of ,february1 or 
at eight on the #aith of ,february1 or  
at seven on the #fth of ,march1 or at   
hours intermediate to these on          
intermediate days4  ,we look first for  
the ,great ,bear towards the north-east1
 as already described1 and thence find  
the ,pole-star2 turning towards which we
 see1 towards the right and downwards1  
the two guardians of the pole 7beta and 
gamma ,urs ,minoris74 ,immediately under
 the ,pole-star is the ,dragon's ,head1 
a conspicuous diamond of stars4 ,just on

 the horizon is ,vega1 scintillating    
brilliantly4 ,overhead is the brilliant 
,capella1 near which the ,milky ,way is 
seen passing down to the horizon on     
either side towards the quarters        
,s4,s4,e4 and ,n4,n4,w4  ,for the       
present our business is with the        
southern heavens1 however4  ,facing the 
south1 we see a brilliant array of      
stars1 ,sirius unmistakeably overshining
 the rest4 ,orion is shining in full    
glory1 his leading brilliant1           
,betelgeuse#b being almost exactly on   
the meridian1 and also almost exactly   
half way between the horizon and the    
zenith4 ,in ,plate #b is given a map of 
this constellation and its              
neighbourhood4  ,let us first turn the  
tube on ,sirius4 ,it is easy to get him 
in the field without the aid of a       
finder4 ,the search will serve to       
illustrate a method often useful when a 
telescope has no finder4 ,having taking 
out the eye-piece--a low-power one1     
suppose--direct the tube nearly towards 

,sirius4 ,on looking through it1 a glare
 of light will be seen within the tube4 
,now1 if the tube be slightly moved     
about1 the light will be seen to wax and
 wane1 according as the tube is more or 
less accurately directed4 ,following    
these indications1 it will be found easy
 to direct the tube1 so that the        
object-glass shall appear full of light4
 ,when this is done1 insert the         
eye-piece1 and the star will be seen in 
the field4  ,but the telescope is out of
 focus1 therefore we must turn the small
 focussing screw4 ,observe the charming 
chromatic changes--green1 and red1 and  
blue light1 purer than the hues of the  
rainbow1 scintillating and coruscating  
with wonderful brilliancy4 ,as we get   
the focus1 the excursions of these light
 flashes diminish until--if the weather 
is favourable--the star is seen1 still  
scintillating1 and much brighter than to
 the naked eye1 but reduced to a small  
disc of light1 surrounded 7in the case  
of so bright a star as ,sirius7 with a  

slight glare4 ,if after obtaining the   
focus the focussing rack work be still  
turned1 we see a coruscating image as   
before4 ,in the case of a very brilliant
 star these coruscations are so charming
 that we may be excused for calling the 
observer's attention to them4 ,the      
subject is not without interest and     
difficulty as an optical one4 ,but the  
astronomer's object is to get rid of all
 these flames and sprays of coloured    
light1 so that he has very little       
sympathy with the admiration which      
,wordsworth is said to have expressed   
for out-of-focus views of the stars4    
,we pass to more legitimate             
observations1 noticing in passing that  
,sirius is a double star1 the companion 
being of the tenth magnitude1 and       
distant about ten seconds from the      
primary4 ,but our beginner is not likely
 to see the companion1 which is a very  
difficult object1 vowing to the         
overpowering brilliancy of the primary4 
,orion affords the observer a splendid  

field of research4 ,it is a             
constellation rich in double and        
multiple stars1 clusters1 and nebul4 ,we
 will begin with an easy object4  ,the  
star delta 7,plate #c71 or ,mintaka1 the
 uppermost of the three stars forming   
the belt1 is a wide double4 ,the primary
 is of the second magnitude1 the        
secondary of the seventh1 both being    
white4  ,the star alpha 7,betelgeuse7 is
 an interesting object1 on account of   
its colour and brilliance1 and as one of
 the most remarkable variables in the   
heavens4 ,it was first observed to be   
variable by ,sir ,john ,herschel in     
#ahcf4 ,at this period its variations   
were most marked and striking4 ,this    
continued until #ahdj1 when the changes 
became much less conspicuous4 ,in       
,january1 #ahdi1 they had recommenced1  
and on ,december #eth1 #aheb1 ,mr4      
,fletcher observed alpha ,orionis       
brighter than ,capella1 and actually the
 largest star in the northern           
hemisphere4 ,that a star so conspicuous1

 and presumably so large1 should present
 such remarkable variations1 is a       
circumstance which adds an additional   
interest to the results which have      
rewarded the spectrum-analysis of this  
star by ,mr4 ,huggins and ,professor    
,miller4 ,it appears that there is      
decisive evidence of the presence in    
this luminary of many elements known to 
exist in our own sun2 amongst others are
 found sodium1 magnesium1 calcium1 iron1
 and bismuth4 ,hydrogen appears to be   
absent1 or1 more correctly1 there are no
 lines in the star's spectrum           
corresponding to those of hydrogen in   
the solar spectrum4 ,secchi considers   
that there is evidence of an actual     
change in the spectrum of the star1 an  
opinion in which ,mr4 ,huggins does not 
coincide4 ,in the telescope ,betelgeuse 
appears as a rich and brilliant gem1    
says ,lassell1 a rich topaz1 in hue and 
brilliancy differing from any that ,i   
have seen4  ,turn next to beta 7,rigel71
 the brightest star below the belt4     

,this is a very noted double1 and will  
severely test our observer's telescope1 
if small4 ,the components are well      
separated 7see ,plate #c71 compared with
 many easier doubles2 the secondary is  
also of the seventh magnitude1 so that  
neither as respects closeness nor       
smallness of the secondary1 is ,rigel a 
difficult object4 ,it is the combination
 of the two features which makes it a   
test-object4 ,kitchener says a          
#a-c_/d-;inch object-glass should show  
,rigel double2 in earlier editions of   
his work he gave #b-c_/d-;inches as the 
necessary aperture4 ,smyth mentions     
,rigel as a test for a #d-;inch         
aperture1 with powers of from #hj to    
#abj4 ,a #c-;inch aperture1 however1    
will certainly show the companion4      
,rigel is an orange star1 the companion 
blue4  ,turn next to lambda the         
northernmost of the set of three stars  
in the head of ,orion4 ,this is a triple
 star1 though an aperture of #c inches  
will show it only as a double4 ,the     

components are #e apart1 the colours    
pale white and violet4 ,with the full   
powers of a #c-a_/b-;inch glass a faint 
companion may be seen above lambda4     
,the star zeta1 the lowest in the belt1 
may be tried with a #c-a_/b-;inch glass4
 ,it is a close double1 the components  
being nearly equal1 and about #b-a_/b   
apart 7see ,plate #c74  ,for a change we
 will now try our telescope on a nebula1
 selecting the great nebula in the      
,sword4 ,the place of this object is    
indicated in ,plate #b4 ,there can be no
 difficulty in finding it since it is   
clearly visible to the naked eye on a   
moonless night--the only sort of night  
on which an observer would care to look 
at nebul4 ,a low power should be        
employed4  ,the nebula is shown in      
,plate #c as ,i have seen it with a     
#c-;inch aperture4 ,we see nothing of   
those complex streams of light which are
 portrayed in the drawings of ,herschel1
 ,bond1 and ,lassell1 but enough to     
excite our interest and wonder4 ,what is

 this marvellous light-cloud8 ,one could
 almost imagine that there was a strange
 prophetic meaning in the words which   
have been translated ,canst thou loose  
the bands of ,orion8 ,telescope after   
telescope had been turned on this       
wonderful object with the hope of       
resolving its light into stars4 ,but it 
proved intractable to ,herschel's great 
reflector1 to ,lassell's #b-;feet       
reflector1 to ,lord ,rosse's #c-;feet   
reflector1 and even partially to the    
great #f-;feet reflector4 ,then we hear 
of its supposed resolution into stars1  
,lord ,rosse himself writing to         
,professor ,nichol1 in #ahdf1 ,i may    
safely say there can be little1 if any1 
doubt as to the resolvability of the    
nebula2--all about the trapezium is a   
mass of stars1 the rest of the nebula   
also abounding with stars1 and          
exhibiting the characteristics of       
resolvability strongly marked4  ,it was 
decided1 therefore1 that assuredly the  
great nebula is a congeries of stars1   

and not a mass of nebulous matter as had
 been surmised by ,sir ,w4 ,herschel4   
,and therefore astronomers were not a   
little surprised when it was proved by  
,mr4 ,huggins' spectrum-analysis that   
the nebula consists of gaseous matter4  
,how widely extended this gaseous       
universe may be we cannot say4 ,the     
general opinion is that the nebul are   
removed far beyond the fixed stars4 ,if 
this were so1 the dimensions of the     
,orion nebula would be indeed enormous1 
far larger probably than those of the   
whole system whereof our sun is a       
member4 ,i believe this view is founded 
on insufficient evidence1 but this would
 not be the place to discuss the        
subject4 ,i shall merely point out that 
the nebula occurs in a region rich in   
stars1 and if it is not1 like the great 
nebula in ,argo1 clustered around a     
remarkable star1 it is found associated 
in a manner which ,i cannot look upon as
 accidental with a set of               
small-magnitude stars1 and notably with 

the trapezium which surrounds that very 
remarkable black gap within the nebula4 
,the fact that the nebula shares the    
proper motion of the trapezium appears  
inexplicable if the nebula is really far
 out in space beyond the trapezium4 ,a  
very small proper motion of the         
trapezium 7alone7 would long since have 
destroyed the remarkable agreement in   
the position of the dark gap and the    
trapezium which has been noticed for so 
many years4  ,but whether belonging to  
our system or far beyond it1 the great  
nebula must have enormous dimensions4 ,a
 vast gaseous system it is1 sustained by
 what arrangements or forces we cannot  
tell1 nor can we know what purposes it  
subserves4 ,mr4 ,huggins' discovery that
 comets have gaseous nuclei1 7so far as 
the two he has yet examined show7 may   
suggest the speculation that in the     
,orion nebula we see a vast system of   
comets travelling in extensive orbits   
around nuclear stars1 and so slowly as  
to exhibit for long intervals of time an

 unchanged figure4 ,but of such         
speculations we may say with ,sir ,j4   
,herschel there is no end4  ,to return  
to our telescopic observations3--,the   
trapezium affords a useful test for the 
light-gathering power of the telescope4 
,large instruments exhibit nine stars4  
,but our observer may be well satisfied 
with his instrument and his eye-sight if
 he can see five with a #c-a_/b-;inch   
aperture4#c ,a good #c-;inch glass shows
 four distinctly4 ,but with smaller     
apertures only three are visible4  ,the 
whole neighbourhood of the great nebula 
will well repay research4 ,the observer 
may sweep over it carefully on any dark 
night with profit4 ,above the nebula is 
the star-cluster #cfb ,h4 ,the star iota
 7double as shown in ,plate #c7 below   
the nebula is involved in a strong      
nebulosity4 ,and in searching over this 
region we meet with delicate double1    
triple1 and multiple stars1 which make  
the survey interesting with almost any  
power that may be applied4  ,above the  

nebula is the star sigma1 a multiple    
star4 ,to an observer with a good       
#c-a_/b-;inch glass sigma appears as an 
octuple star4 ,it is well seen1 however1
 as a fine multiple star with a smaller 
aperture4 ,some of the stars of this    
group appear to be variable4  ,the star 
rho ,orionis is an unequal1 easy double1
 the components being separated by      
nearly seven seconds4 ,the primary is   
orange1 the smaller star smalt-blue 7see
 ,plate #c74  ,the middle star of the   
belt 7epsilon7 has a distant blue       
companion4 ,this star1 like iota1 is    
nebulous4 ,in fact1 the whole region    
within the triangle formed by stars     
gamma1 kappa and beta is full of        
nebulous double and multiple stars1     
whose aggregation in this region ,i do  
not consider wholly accidental4  ,we    
have not explored half the wealth of    
,orion1 but leave much for future       
observation4 ,we must turn1 however1 to 
other constellations4  ,below ,orion is 
,lepus1 the ,hare1 a small constellation

 containing some remarkable doubles4    
,among these we may note xi1 a white    
star with a scarlet companion2 gamma1 a 
yellow and garnet double2 and iota1 a   
double star1 white and pale violet1 with
 a distant red companion4 ,the star     
kappa ,leporis is a rather close double1
 white with a small green companion4    
,the intensely red star ,r ,leporis 7a  
variable7 will be found in the position 
indicated in the map4  ,still keeping   
within the boundary of our map1 we may  
next turn to the fine cluster #b ,h     
7vii47 in ,monoceros4 ,this cluster is  
visible to the naked eye1 and will be   
easily found4 ,the nebula #b ,h 7iv47 is
 a remarkable one with a powerful       
telescope4  ,the star #aa ,monocerotis  
is a fine triple star described by the  
elder ,herschel as one of the finest    
sights in the heavens4 ,our observer1   
however1 will see it as a double 7see   
,plate #c74 delta ,monocerotis is an    
easy double1 yellow and lavender4  ,we  
may now leave the region covered by the 

map and take a survey of the heavens for
 some objects well seen at this season4 
,towards the south-east1 high up above  
the horizon1 we see the twin-stars      
,castor and ,pollux4 ,the upper is      
,castor1 the finest double star visible 
in the northern heavens4 ,the components
 are nearly equal and rather more than  
#e apart 7see ,plate #c74 ,both are     
white according to the best observers1  
but the smaller is thought by some to be
 slightly greenish4  ,pollux is a coarse
 but fine triple star 7in large         
instruments multiple74 ,the components  
orange1 grey1 and lilac4  ,there are    
many other fine objects in ,gemini1 but 
we pass to ,cancer4  ,the fine cluster  
,prsepe in ,cancer may easily be found  
as it is distinctly visible to the naked
 eye in the position shown in ,plate #a1
 ,map ,i4 ,in the telescope it is seen  
as shown in ,plate #c4  ,the star iota  
,cancri is a wide double1 the colours   
orange and blue4  ,procyon1 the         
first-magnitude star between ,prsepe and

 ,sirius1 is finely coloured--yellow    
with a distant orange companion1 which  
appears to be variable4  ,below the     
,twins1 almost in a line with them1 is  
the star alpha ,hydr1 called ,al ,fard1 
or the ,solitary ,one4 ,it is a #bnd    
magnitude variable4 ,i mention it1      
however1 not on its own account1 but as 
a guide to the fine double epsilon      
,hydr4 ,this star is the middle one of a
 group of three1 lying between ,pollux  
and ,al ,fard rather nearer the latter4 
,the components of epsilon ,hydr are    
separated by about #c-a_/b 7see ,plate  
#c74 ,the primary is of the fourth1 the 
companion of the eighth magnitude2 the  
former is yellow1 the latter a ruddy    
purple4 ,the period of epsilon ,hydr is 
about #dej years4  ,the constellation   
,leo ,minor1 now due east and about     
midway between the horizon and the      
zenith1 is well worth sweeping over4 ,it
 contains several fine fields4  ,let us 
next turn to the western heavens4 ,here 
there are some noteworthy objects4  ,to 

begin with1 there are the ,pleiades1    
showing to the naked eye only six or    
seven stars4 ,in the telescope the      
,pleiades appear as shown in ,plate #c4 
,the ,hyades also show some fine fields 
with low powers4  ,aldebaran1 the       
principal star of the ,hyades1 as also  
of the constellation ,taurus1 is a noted
 red star4 ,it is chiefly remarkable for
 the close spectroscopic analysis to    
which it has been subjected by ,messrs4 
,huggins and ,miller4 ,unlike           
,betelgeuse1 the spectrum of ,aldebaran 
exhibits the lines corresponding to     
hydrogen1 and no less than eight        
metals--sodium1 magnesium1 calcium1     
iron1 bismuth1 tellurium1 antimony1 and 
mercury1 are proved to exist in the     
constitution of this brilliant red star4
  ,on the right of ,aldebaran1 in the   
position indicated in ,plate #a1 ,map   
,i41 are the stars zeta and beta ,tauri4
 ,if with a low power the observer sweep
 from zeta towards beta1 he will soon   
find--not far from zeta 7at a distance  

of about one-sixth of the distance      
separating beta from zeta71 the         
celebrated ,crab nebula1 known as #a ,m4
 ,this was the first nebula discovered  
by ,messier1 and its discovery led to   
the formation of his catalogue of #ajc  
nebul4 ,in a small telescope this object
 appears as a nebulous light of oval    
form1 no traces being seen of the wisps 
and sprays of light presented in ,lord  
,rosse's well known picture of the      
nebula4  ,here ,i shall conclude the    
labours of our first half-hour among the
 stars1 noticing that the examination of
 ,plate #a will show what other         
constellations besides those here       
considered are well situated for        
observation at this season4 ,it will be 
remarked that many constellations well  
seen in the third half-hour 7,chapter   
,,iv47 are favourably seen in the first 
also1 and vice vers4 ,for instance1 the 
constellation ,ursa ,major well-placed  
towards the north-east in the first     
quarter of the year1 is equally         

well-placed towards the north-west in   
the third1 and similarly of the         
constellation ,cassiopeia4 ,the same    
relation connects the second and fourth 
quarters of the year4  ,illustration3   
,,plate ,,iii4     ,,chapter ,,iii4  ,a 
,,half-,,hour ,,with ,,lyra1 ,,hercules1
 ,,corvus1 ,,crater1 ,,etc4   ,the      
observations now to be commenced are    
supposed to take place during the second
 quarter of the year1--at ten o'clock on
 the #bjth of ,april1 or at nine on the 
#eth of ,may1 or at eight on the #bast  
of ,may1 or at seven on the #eth of     
,june1 or at hours intermediate to these
 on intermediate days4  ,we again look  
first for the ,great ,bear1 now near the
 zenith1 and thence find the ,pole-star4
 ,turning towards the north1 we see     
,cassiopeia between the ,pole-star and  
the horizon4 ,towards the north-west is 
the brilliant ,capella1 and towards the 
north-east the equally brilliant ,vega1 
beneath which1 and somewhat northerly1  
is the cross in ,cygnus4 ,the ,milky    

,way passes from the eastern horizon    
towards the north 7low down71 and so    
round to the western horizon4  ,in      
selecting a region for special          
observation1 we shall adopt a different 
plan from that used in the preceding    
half-hour4 ,the region on the equator   
and towards the south is indeed         
particularly interesting1 since it      
includes the nebular region in ,virgo4  
,within this space nebul are clustered  
more closely than over any corresponding
 space in the heavens1 save only the    
greater ,magellanic cloud4 ,but to the  
observer with telescopes of moderate    
power these nebul present few features  
of special interest2 and there are      
regions of the sky now well situated for
 observation1 which1 at most other      
epochs are either low down towards the  
horizon or inconveniently near to the   
zenith4 ,we shall therefore select one  
of these1 the region included in the    
second map of ,plate #b1 and the        
neighbouring part of the celestial      

sphere4  ,at any of the hours above     
named1 the constellation ,hercules lies 
towards the east4 ,a quadrant taken from
 the zenith to the eastern horizon      
passes close to the last star 7eta7 of  
the ,great ,bear's tail1 through beta1 a
 star in ,bootes' head1 near beta       
,herculis1 between the two ,alphas which
 mark the heads of ,hercules and        
,ophiuchus1 and so past beta ,ophiuchi1 
a third-magnitude star near the horizon4
 ,and here we may turn aside for a      
moment to notice the remarkable vertical
 row of six conspicuous stars towards   
the east-south-east2 these are1 counting
 them in order from the horizon1 zeta1  
epsilon1 and delta ,ophiuchi1 epsilon1  
alpha1 and delta ,serpentis4  ,let the  
telescope first be directed towards     
,vega4 ,this orb presents a brilliant   
appearance in the telescope4 ,its colour
 is a bluish-white4 ,in an ordinary     
telescope ,vega appears as a single     
star1 but with a large object-glass two 
distant small companions are seen4 ,a   

nine-inch glass shows also two small    
companions within a few seconds of      
,vega4 ,in the great ,harvard refractor 
,vega is seen with no less than         
thirty-five companions4 ,i imagine that 
all these stars1 and others which can be
 seen in neighbouring fields1 indicate  
the association of ,vega with the       
neighbouring stream of the ,milky ,way4 
,let our observer now direct his        
telescope to the star epsilon ,lyr4 ,or 
rather1 let him first closely examine   
this star with the naked eye4 ,the star 
is easily identified1 since it lies to  
the left of ,vega1 forming with zeta a  
small equilateral triangle4 ,a careful  
scrutiny suffices to indicate a         
peculiarity in this star4 ,if our       
observer possesses very good eye-sight1 
he will distinctly recognise it as a    
naked-eye double2 but more probably he  
will only notice that it appears        
lengthened in a north and south         
direction4#d ,in the finder the star is 
easily divided4 ,applying a low power to

 the telescope itself1 we see epsilon   
,lyr as a wide double1 the line joining 
the components lying nearly north and   
south4 ,the southernmost component 7the 
upper in the figure7 is called          
epsilon#a1 the other epsilon#b4 ,seen as
 a double1 both components appear white4
  ,now1 if the observer's telescope is  
sufficiently powerful1 each of the      
components may be seen to be itself     
double4 ,first try epsilon#a1 the       
northern pair4 ,the line joining the    
components is directed as shown in      
,plate #c4 ,the distance between them is
 #cb1 their magnitudes #e and #f-a_/b1  
and their colours yellow and ruddy4 ,if 
the observer succeeds in seeing         
epsilon#a fairly divided1 he will       
probably not fail in detecting the      
duplicity of epsilon#b1 though this is a
 rather closer pair1 the distance       
between the components being only #bf4  
,the magnitudes are #e and #e-a_/b1 both
 being white4 ,between epsilon#a and    
epsilon#b are three faint stars1        

possibly forming with the quadruple a   
single system4  ,let us next turn to the
 third star of the equilateral triangle 
mentioned above--viz4 to the star zeta  
,lyr4 ,this is a splendid but easy      
double4 ,it is figured in ,plate #c1 but
 it must be noticed that the figure of  
zeta and the other nine small figures   
are not drawn on the same scale as      
epsilon ,lyr4 ,the actual distance      
between the components of zeta ,lyra is 
#dd1 or about one-fourth of the distance
 separating epsilon#a from epsilon#b4   
,the components of zeta are very nearly 
equal in magnitude1 in colour topaz and 
green1 the topaz component being        
estimated as of the fifth magnitude1 the
 green component intermediate between   
the fifth and sixth magnitudes4  ,we may
 now turn to a star not figured in the  
map1 but readily found4 ,it will be     
noticed that the stars epsilon1 alpha1  
beta1 and gamma form1 with two small    
stars towards the left1 a somewhat      
regular hexagonal figure--a hexagon1 in 

fact1 having three equal long sides and 
three nearly equal short sides          
alternating with the others4 ,the star  
eta ,lyr forms the angle next to        
epsilon4 ,it is a wide and unequal      
double1 as figured in ,plate #c4 ,the   
larger component is azure blue2 the     
smaller is violet1 and1 being only of   
the ninth magnitude1 is somewhat        
difficult to catch with apertures under 
#c inches4  ,the star delta#b ,lyr is   
orange1 delta#a blue4 ,in the same field
 with these are seen many other stars4  
,the stars gamma#a and gamma#b may also 
be seen in a single field1 the distance 
between them being about half the moon's
 mean diameter4 ,the former is          
quadruple1 the components being yellow1 
bluish1 pale blue1 and blue4  ,turn next
 to the stars beta and gamma ,lyr1 the  
former a multiple1 the latter an unequal
 double star4 ,it is not1 however1 in   
these respects that these stars are     
chiefly interesting1 but for their      
variability4 ,the variability of gamma  

has not indeed been fully established1  
though it is certain that1 having once  
been less bright1 gamma is now          
considerably brighter than beta4 ,the   
change1 however1 may be due to the      
variation of beta alone4 ,this star is  
one of the most remarkable variables    
known4 ,its period is #ab;d4 #ba;h4     
#ecm4 #ajs4 ,in this time it passes from
 a maximum brilliancy--that of a star of
 the #cd magnitude--to a minimum lustre 
equal to that of a star of the #dc      
magnitude1 thence to the same maximum   
brilliancy as before1 thence to another 
minimum of lustre--that of a star of the
 #de magnitude--and so to its maximum   
lustre again1 when the cycle of changes 
recommences4 ,these remarkable changes  
seem to point to the existence of two   
unequal dark satellites1 whose          
dimensions bear a much greater          
proportion to those of the bright       
components of beta ,lyr than the        
dimensions of the members of the ,solar 
,system bear to those of the sun4 ,in   

this case1 at any rate1 the conjecture  
hazarded about ,algol1 that the star    
revolves around a dark central orb1     
would be insufficient to account for the
 observed variation4  ,nearly midway    
between beta and gamma lies the         
wonderful ring-nebula #eg ,m1 of which  
an imperfect idea will be conveyed by   
the last figure of ,plate #c4 ,this     
nebula was discovered in #aggb1 by      
,darquier1 at ,toulouse4 ,it is seen as 
a ring of light with very moderate      
telescopic power4 ,in a good            
#c-a_/b-;inch telescope the nebula      
exhibits a mottled appearance and a     
sparkling light4 ,larger instruments    
exhibit a faint light within the ring2  
and in ,lord ,rosse's great ,telescope  
wisps of stars are seen within1 and     
faint streaks of light stream from the  
outer border of the ring4 ,this nebula  
has been subjected to spectrum-analysis 
by ,mr4 ,huggins4 ,it turns out to be a 
gaseous nebula6 ,in fact1 ring-nebul--of
 which only seven have been             

detected--seem to belong to the same    
class as the planetary nebul1 all of    
which exhibit the line-spectrum         
indicative of gaseity4 ,the brightest of
 the three lines seen in the spectrum of
 the ring-nebula in ,lyra presents a    
rather peculiar appearance1 since it    
consists1 says ,mr4 ,huggins1 of two    
bright dots1 corresponding to sections  
of the ring1 and between these there is 
not darkness1 but an excessively faint  
line joining them4 ,this observation    
makes it probable that the faint        
nebulous matter occupying the central   
portion is similar in constitution to   
that of the ring4  ,the constellation   
,hercules also contains many very       
interesting objects4 ,let us first      
inspect a nebula presenting a remarkable
 contrast with that just described4 ,i  
refer to the nebula #ac ,m1 known as    
,halley's nebula 7,plate #c74 ,this     
nebula is visible to the naked eye1 and 
in a good telescope it is a most        
wonderful object3 perhaps no one ever   

saw it for the first time without       
uttering a shout of wonder4 ,it requires
 a very powerful telescope completely to
 resolve this fine nebula1 but the      
outlying streamers may be resolved with 
a good #c-;inch telescope4 ,sir ,w4     
,herschel considered that the number of 
the stars composing this wonderful      
object was at least #ad1jjj4 ,the       
accepted views respecting nebul would   
place this and other clusters far beyond
 the limits of our sidereal system1 and 
would make the component stars not very 
unequal 7on the average7 to our own sun4
 ,it seems to me far more probable1 on  
the contrary1 that the cluster belongs  
to our own system1 and that its         
components are very much smaller than   
the average of separate stars4 ,perhaps 
the whole mass of the cluster does not  
exceed that of an average               
first-magnitude star4  ,the nebul #ib ,m
 and #ej ,h may be found1 after a little
 searching1 from the positions indicated
 in the map4 ,they are both well worthy 

of study1 the former being a very bright
 globular cluster1 the latter a bright  
and large round nebula4 ,the spectra of 
these1 as of the great cluster1 resemble
 the solar spectrum1 being continuous1  
though1 of course1 very much fainter4   
,the star delta ,herculis 7seen at the  
bottom of the map7 is a wide and easy   
double--a beautiful object4 ,the        
components1 situated as shown in ,plate 
#c1 are of the fourth and eighth        
magnitude1 and coloured respectively    
greenish-white and grape-red4  ,the star
 kappa ,herculis is not shown in the    
map1 but may be very readily found1     
lying between the two gammas1 gamma     
,herculis and gamma ,serpentis 7see     
,frontispiece1 ,map #b71 rather nearer  
the latter4 ,it is a wide double1 the   
components of fifth and seventh         
magnitude1 the larger yellowish-white1  
the smaller ruddy yellow4#e  ,ras       
,algethi1 or alpha ,herculis1 is also   
beyond the limits of the map1 but may be
 easily found by means of ,map #b1      

,frontispiece4 ,it is1 properly         
speaking1 a multiple star4 ,considered  
as a double1 the arrangement of the     
components is that shown in ,plate #c4  
,the larger is of magnitude #c-a_/b1 the
 smaller of magnitude #e-a_/b2 the      
former orange1 the latter emerald4 ,the 
companion stars are small1 and require a
 good telescope to be well seen4 ,ras   
,algethi is a variable1 changing from   
magnitude #c to magnitude #c-a_/b in a  
period of #ff-a_/c days4  ,the star rho 
,herculis is a closer double4 ,the      
components are #cg apart1 and situated  
as shown in ,plate #c4 ,the larger is of
 magnitude #d1 the smaller #e-a_/b2 the 
former bluish-white1 the latter pale    
emerald4  ,there are other objects      
within the range of our map which are   
well worthy of study4 ,such are mu      
,draconis1 a beautiful miniature of     
,castor2 gamma#a and gamma#b ,draconis1 
a wide double1 the distance between the 
components being nearly #fb 7both grey72
 and gamma#a and gamma#b ,coron1 a      

naked-eye double1 the components being  
#f' apart1 and each double with a good  
#c-;inch telescope4  ,we turn1 however1 
to another region of the sky4 ,low down1
 towards the south is seen the small    
constellation ,corvus1 recognised by its
 irregular quadrilateral of stars4 ,of  
the two upper stars1 the left-hand one  
is ,algorab1 a wide double1 the         
components placed as in ,plate #c1 #bce 
apart1 the larger of magnitude #c1 the  
smaller #h-a_/b1 the colours pale yellow
 and purple4  ,there is a red star in   
this neighbourhood which is well worth  
looking for4 ,to the right of ,corvus is
 the constellation ,crater1 easily      
recognised as forming a tolerably       
well-marked small group4 ,the star      
,alkes1 or alpha ,crateris1 must first  
be found4 ,it is far from being the     
brightest star in the constellation1 and
 may be assumed to have diminished      
considerably in brilliancy since it was 
entitled alpha by ,bayer4 ,it will      
easily be found1 however1 by means of   

the observer's star maps4 ,if now the   
telescope be directed to ,alkes1 there  
will be found1 following him at a       
distance of #dbe s1 and about one minute
 southerly1 a small red star1 ,r4       
,crateris4 ,like most red stars1 this   
one is a variable4 ,a somewhat smaller  
blue star may be seen in the same field4
  ,there is another red star which may  
be found pretty easily at this season4  
,first find the stars eta and omicron   
,leonis1 the former forming with        
,regulus 7now lying towards the         
south-west1 and almost exactly midway   
between the zenith and the horizon7 the 
handle of the ,sickle in ,leo1 the other
 farther off from ,regulus towards the  
right1 but lower down4 ,now sweep from  
omicron towards eta with a low power4#f 
,there will be found a sixth-magnitude  
star about one-fourth of the way from   
omicron to eta4 ,south1 following this1 
will be found a group of four stars1 of 
which one is crimson4 ,this is the star 
,r ,leonis4 ,like ,r ,crateris and ,r   

,leporis it is variable4  ,next1 let the
 observer turn towards the south again4 
,above ,corvus1 in the position shown in
 the ,frontispiece1 there are to be seen
 five stars1 forming a sort of wide ,v  
with somewhat bowed legs4 ,at the angle 
is the star gamma ,virginis1 a noted    
double4 ,in #agef the components were   
#f-a_/b seconds apart4 ,they gradually  
approached till1 in #ahcf1 they could   
not be separated by the largest         
telescopes4 ,since then they have been  
separating1 and they are now #d-a_/b    
seconds apart1 situated as shown in     
,plate #c4 ,they are nearly equal in    
magnitude 7#d71 and both pale yellow4   
,the star gamma ,leonis is a closer and 
more beautiful double4 ,it will be found
 above ,regulus1 and is the brightest   
star on the blade of the ,sickle4 ,the  
components are separated by about       
#c-a_/e seconds1 the larger of the      
second1 the smaller of the fourth       
magnitude2 the former yellow-orange1 the
 latter greenish-yellow4  ,lastly1 the  

star iota ,leonis may be tried4 ,it will
 be a pretty severe test for our        
observer's telescope1 the components    
being only #bd apart1 and the smaller   
scarcely exceeding the eighth magnitude4
 ,the brighter 7fourth magnitude7 is    
pale yellow1 the other light blue4      
,,chapter ,,iv4  ,a ,,half-,,hour ,,with
 ,,bootes1 ,,scorpio1 ,,ophiuchus1      
,,etc4   ,we now commence a series of   
observations suited to the third quarter
 of the year1 and to the following      
hours3--,ten o'clock on the #bbnd of    
,july2 nine on the #hth of ,august2     
eight on the #bcrd of ,august2 seven on 
the #hth of ,october2 and intermediate  
hours on days intermediate to these4    
,we look first for the ,great ,bear     
towards the north-west1 and thence find 
the ,pole-star4 ,turning towards the    
north we see ,capella and beta ,aurig   
low down and slightly towards the left  
of the exact north point4 ,the ,milky   
,way crosses the horizon towards the    
north-north-east and passes to the      

opposite point of the compass1 attaining
 its highest point above the horizon    
towards east-south-east4 ,this part of  
the ,milky ,way is well worth observing1
 being marked by singular variations of 
brilliancy4 ,near ,arided 7the principal
 star of ,cygnus1 and now lying due     
east--some twenty-five degrees from the 
zenith7 there is seen a straight dark   
rift1 and near this space is another    
larger cavity1 which has been termed the
 northern ,coal-sack4 ,the space between
 gamma1 delta1 and beta ,cygni is       
covered by a large oval mass1           
exceedingly rich and brilliant4 ,the    
neighbouring branch1 extending from     
epsilon ,cygni1 is far less conspicuous 
here1 but near ,sagitta becomes brighter
 than the other1 which in this          
neighbourhood suddenly loses its        
brilliancy and fading gradually beyond  
this point becomes invisible near beta  
,ophiuchi4 ,the continuous stream       
becomes patchy--in parts very           
brilliant--where it crosses ,aquila and 

,clypeus4 ,in this neighbourhood the    
other stream reappears1 passing over a  
region very rich in stars4 ,we see now  
the greatest extent of the ,milky ,way1 
towards this part of its length1 ever   
visible in our latitudes--just as in    
spring we see its greatest extent       
towards ,monoceros and ,argo4           
,illustration3 ,,plate ,,iv4  ,i may    
note here in passing that ,sir ,john    
,herschel's delineation of the northern 
portion of the ,milky ,way1 though a    
great improvement on the views given in 
former works1 seems to require revision1
 and especially as respects the very    
remarkable patches and streaks which    
characterise the portion extending over 
,cepheus and ,cygnus4 ,it seems to me1  
also1 that the evidence on which it has 
been urged that the stars composing the 
,milky ,way are 7on an average7         
comparable in magnitude to our own sun1 
or to stars of the leading magnitudes1  
is imperfect4 ,i believe1 for instance1 
that the brilliant oval of milky light  

in ,cygnus comes from stars intimately  
associated with the leading stars in    
that constellation1 and not far removed 
in space 7proportionately7 beyond them4 
,of course1 if this be the case1 the    
stars1 whose combined light forms the   
patch of milky light1 must be far       
smaller than the leading brilliants of  
,cygnus4 ,however1 this is not the place
 to enter on speculations of this sort2 
,i return therefore to the business we  
have more immediately in hand4  ,towards
 the east is the square of ,pegasus low 
down towards the horizon4 ,towards the  
south is ,scorpio1 distinguished by the 
red and brilliant ,antares1 and by a    
train of conspicuous stars4 ,towards the
 west is ,bootes1 his leading           
brilliant--the ruddy ,arcturus--lying   
somewhat nearer the horizon than the    
zenith1 and slightly south of west4     
,bootes as a constellation is easily    
found if we remember that he is         
delineated as chasing away the ,greater 
,bear4 ,thus at present he is seen in a 

slightly inclined position1 his head    
7marked by the third-magnitude star     
beta7 lying due west1 some thirty       
degrees from the zenith4 ,it has always 
appeared to me1 by the way1 that ,bootes
 originally had nobler proportions than 
astronomers now assign to him4 ,it is   
known that ,canes ,venatici now occupy  
the place of an upraised arm of ,bootes1
 and ,i imagine that ,corona ,borealis1 
though undoubtedly a very ancient       
constellation1 occupies the place of his
 other arm4 ,giving to the constellation
 the extent thus implied1 it exhibits   
7better than most constellations7 the   
character assigned to it4 ,one can      
readily picture to oneself the figure of
 a ,herdsman with upraised arms driving 
,ursa ,major before him4 ,this view is  
confirmed1 ,i think1 by the fact that   
the ,arabs called this constellation the
 ,vociferator4  ,bootes contains many   
beautiful objects4 ,partly on this      
account1 and partly because this is a   
constellation with which the observer   

should be specially familiar1 a map of  
it is given in ,plate #d4  ,arcturus has
 a distant pale lilac companion1 and is 
in other respects a remarkable and      
interesting object4 ,it is of a ruddy   
yellow colour4 ,schmidt1 indeed1        
considers that the star has changed     
colour of late years1 and that whereas  
it was once very red it is now a yellow 
star4 ,this opinion does not seem well  
grounded1 however4 ,the star may have   
been more ruddy once than now1 though no
 other observer has noticed such a      
peculiarity2 but it is certainly not a  
pure yellow star at present 7at any rate
 as seen in our latitude74 ,owing       
probably to the difference of colour    
between ,vega1 ,capella and ,arcturus1  
photometricians have not been perfectly 
agreed as to the relative brilliancy of 
these objects4 ,some consider ,vega the 
most brilliant star in the northern     
heavens1 while others assign the        
superiority to ,capella4 ,the majority1 
however1 consider ,arcturus the leading 

northern brilliant1 and in the whole    
heavens place three only before him1    
viz41 ,sirius1 ,canopus1 and alpha      
,centauri4 ,arcturus is remarkable in   
other respects4 ,his proper motion is   
very considerable1 so great in fact that
 since the time of ,ptolemy the         
southerly motion 7alone7 of ,arcturus   
has carried him over a space nearly half
 as great again as the moon's apparent  
diameter4 ,one might expect that so     
brilliant a star1 apparently travelling 
at a rate so great compared with the    
average proper motions of the stars1    
must be comparatively near to us4 ,this1
 however1 has not been found to be the  
case4 ,arcturus is1 indeed1 one of the  
stars whose distance it has been found  
possible to estimate roughly4 ,but he is
 found to be some three times as far    
from us as the small star #fa ,cygni1   
and more than seven times as far from us
 as alpha ,centauri4  ,the star delta   
,bootis is a wide and unequal double1   
the smaller component being only of the 

ninth magnitude4  ,above ,alkaid the    
last star in the tail of the ,greater   
,bear1 there will be noticed three small
 stars4 ,these are theta1 iota1 and     
kappa ,bootis1 and are usually placed in
 star-maps near the upraised hand of the
 ,herdsman4 ,the two which lie next to  
,alkaid1 iota and kappa1 are interesting
 doubles4 ,the former is a wide double  
7see ,plate #e71 the magnitudes of      
components #d and #h1 their colours     
yellow and white4 ,the larger star of   
this pair is itself double4 ,the star   
kappa ,bootis is not so wide a double   
7see ,plate #e71 the magnitudes of the  
components #e and #h1 their colours     
white and faint blue--a beautiful       
object4  ,the star xi ,bootis is an     
exceedingly interesting object4 ,it is  
double1 the colours of the components   
being orange-yellow and ruddy purple1   
their magnitudes #c-a_/b and #f-a_/b4   
,when this star was first observed by   
,herschel in #aghj the position of the  
components was quite different from that

 presented in ,plate #e4 ,they were also
 much closer1 being separated by a      
distance of less than #c-a_/b seconds4  
,since that time the smaller component  
has traversed nearly a full quadrant1   
its distance from its primary first     
increasing1 till in #ahca the stars were
 nearly #g-a_/b seconds apart1 and      
thence slowly diminishing1 so that at   
present the stars are less than #e      
seconds apart4 ,the period usually      
assigned to the revolution of this      
binary system is #aag years1 and the    
period of peri-astral passage is said to
 be #aggi4 ,it appears to me1 however1  
that the period should be about #ajh    
years1 the epoch of last peri-astral    
passage #aggg and of next peri-astral   
passage1 therefore1 #ahhe4 ,the angular 
motion of the secondary round the       
primary is now rapidly increasing1 and  
the distance between the components is  
rapidly diminishing1 so that in a few   
years a powerful telescope will be      
required to separate the pair4  ,not far

 from xi is pi ,bootis1 represented in  
,plate #e as a somewhat closer double1  
but in reality--now at any rate--a      
slightly wider pair1 since the distance 
between the components of xi has greatly
 diminished of late4 ,both the          
components of pi are white1 and their   
magnitudes are #c-a_/b and #f4  ,we     
shall next turn to an exceedingly       
beautiful and delicate object1 the      
double star epsilon ,bootis1 known also 
as ,mirac and1 on account of its extreme
 beauty1 called ,pulcherrima by ,admiral
 ,smyth4 ,the components of this        
beautiful double are of the third and   
seventh magnitude1 the primary orange1  
the secondary sea-green4 ,the distance  
separating the components is about #c   
seconds1 perhaps more2 it appears to    
have been slowly increasing during the  
past ten or twelve years4 ,smyth assigns
 to this system a period of revolution  
of #ihj years1 but there can be little  
doubt that the true period is largely in
 excess of this estimate4 ,observers in 

southern latitudes consider that the    
colours of the components are yellow and
 blue1 not orange and green as most of  
our northern observers have estimated   
them4  ,a little beyond the lower       
left-hand corner of the map is the star 
delta ,serpentis1 in the position shown 
in the ,frontispiece1 ,map #c4 ,this is 
the star which at the hour and season   
depicted in ,map #b formed the uppermost
 of a vertical row of stars1 which has  
now assumed an almost horizontal        
position4 ,the components of delta      
,serpentis are about #c-a_/b seconds    
apart1 their magnitudes #c and #e1 both 
white4  ,the stars theta#a and theta#b  
,serpentis form a wide double1 the      
distance between the components being   
#ba-a_/b seconds4 ,they are nearly equal
 in magnitude1 the primary being        
#d-a_/b1 the secondary #e4 ,both are    
yellow1 the primary being of a paler    
yellow colour than the smaller star4    
,but the observer may not know where to 
look for theta ,serpentis1 since it     

falls in a part of the constellation    
quite separated from that part in which 
delta ,serpentis lies4 ,in fact theta   
lies on the extreme easterly verge of   
the eastern half of the constellation4  
,it is to be looked for at about the    
same elevation as the brilliant ,altair1
 and 7as to azimuth7 about midway       
between ,altair and the south4  ,the    
stars alpha#a and alpha#b ,libr form a  
wide double1 perhaps just separable by  
the naked eye in very favourable        
weather4 ,the larger component is of the
 third1 the smaller of the sixth        
magnitude1 the former yellow the latter 
light grey4  ,the star beta ,libr is a  
beautiful light-green star to the naked 
eye2 in the telescope a wide double1    
pale emerald and light blue4  ,in       
,scorpio there are several very         
beautiful objects3--  ,the star ,antares
 or ,cor ,scorpionis is one of the most 
beautiful of the red stars4 ,it has been
 termed the ,sirius of red stars1 a term
 better merited perhaps by ,aldebaran1  

save for this that1 in our latitude1    
,antares is1 like ,sirius1 always seen  
as a brilliant scintillator 7because    
always low down71 whereas ,aldebaran    
rises high above the horizon4 ,antares  
is a double star1 its companion being a 
minute green star4 ,in southern         
latitudes the companion of ,antares may 
be seen with a good #d-;inch1 but in our
 latitudes a larger opening is wanted4  
,mr4 ,dawes once saw the companion of   
,antares shining alone for seven        
seconds1 the primary being hidden by the
 moon4 ,he found that the colour of the 
secondary is not merely the effect of   
contrast1 but that this small star is   
really a green sun4  ,the star beta     
,scorpionis is a fine double1 the       
components #aca apart1 their magnitudes 
#b and #e-a_/b1 colours white and lilac4
 ,it has been supposed that this pair is
 only an optical double1 but a long time
 must elapse before a decisive opinion  
can be pronounced on such a point4  ,the
 star sigma ,scorpionis is a wider but  

much more difficult double1 the smaller 
component being below the #ith          
magnitude4 ,the colour of the primary   
7#d7 is white1 that of the secondary    
maroon4  ,the star xi ,scorpionis is a  
neat double1 the components #gb apart1  
their magnitudes #d-a_/b and #g-a_/b1   
their colours white and grey4 ,this star
 is really triple1 a fifth-magnitude    
star lying close to the primary4  ,in   
,ophiuchus1 a constellation covering a  
wide space immediately above ,scorpio1  
there are several fine doubles4 ,among  
others--  #ci ,ophiuchi1 distance       
between components #aba1 their          
magnitudes #e-a_/b and #g-a_/b1 their   
colours orange and blue4  ,the star #gj 
,ophiuchi1 a fourth-magnitude star on   
the right shoulder of ,ophiuchus1 is a  
noted double4 ,the distance between the 
components about #e-a_/b1 their         
magnitudes #d-a_/b and #g1 the colours  
yellow and red4 ,the pair form a system 
whose period of revolution is about #ie 
years4  #cf ,ophiuchi 7variable71       

distance #eb1 magnitudes #d-a_/b and    
#f-a_/b1 colours red and yellow4  rho   
,opiuchi1 distance #d1 colours yellow   
and blue1 magnitudes #e and #g4         
,between alpha and beta ,scorpionis the 
fine nebula #hj ,m may be looked for4   
7,or more closely thus3--below beta is  
the wide ,double omega#a and omega#b    
,scorpionis2 about as far to the right  
of ,antares is the star sigma           
,scorpionis1 and immediately above this 
is the fifth-magnitude star #ai47 ,the  
nebula we seek lies between #ai and     
omega1 nearer to #ai 7about two-fifths  
of the way towards omega74 ,this nebula 
is described by ,sir ,w4 ,herschel as   
the richest and most condensed mass of  
stars which the firmament offers to the 
contemplation of astronomers4  ,there   
are two other objects conveniently      
situated for observation1 which the     
observer may now turn to4 ,the first is 
the great cluster in the sword-hand of  
,perseus 7see ,plate #d71 now lying     
about #bh above the horizon between     

,n4,e4 and ,n4,n4,e4 ,the stars gamma   
and delta ,cassiopei 7see ,map #c of    
,frontispiece7 point towards this       
cluster1 which is rather farther from   
delta than delta from gamma1 and a      
little south of the produced line from  
these stars4 ,the cluster is well seen  
with the naked eye1 even in nearly full 
moonlight4 ,in a telescope of moderate  
power this cluster is a magnificent     
object1 and no telescope has yet        
revealed its full glory4 ,the view in   
,plate #e gives but the faintest        
conception of the glories of chi        
,persei4 ,sir ,w4 ,herschel tried in    
vain to gauge the depths of this cluster
 with his most powerful telescope4 ,he  
spoke of the most distant parts as      
sending light to us which must have     
started #djjj or #ejjj years ago4 ,but  
it appears improbable that the cluster  
has in reality so enormous a            
longitudinal extension compared with its
 transverse section as this view would  
imply4 ,on the contrary1 ,i think we may

 gather from the appearance of this     
cluster1 that stars are far less uniform
 in size than has been commonly         
supposed1 and that the mere             
irresolvability of a cluster is no proof
 of excessive distance4 ,it is unlikely 
that the faintest component of the      
cluster is farther off than the         
brightest 7a seventh-magnitude star7 in 
the proportion of more than about #bj to
 #ai1 while the ordinary estimate of    
star magnitudes1 applied by ,herschel1  
gave a proportion of #bj or #cj to #a at
 least4 ,i can no more believe that the 
components of this cluster are stars    
greatly varying in distance1 but        
accidentally seen in nearly the same    
direction1 7or that they form an        
enormously long system turned by        
accident directly towards the earth71   
than ,i could look on the association of
 several thousand persons in the form of
 a procession as a fortuitous           
arrangement4  ,next there is the great  
nebula in ,andromeda--known as the      

transcendantly beautiful queen of the   
nebul4 ,it will not be difficult to find
 this object4 ,the stars epsilon and    
delta ,cassiopei 7,map #c1              
,frontispiece7 point to the star beta   
,andromed4 ,almost in a vertical line   
above this star are two fourth-magnitude
 stars mu and gamma1 and close above nu1
 a little to the right1 is the object we
 seek--visible to the naked eye as a    
faint misty spot4 ,to tell the truth1   
the transcendantly beautiful queen of   
the nebul is rather a disappointing     
object in an ordinary telescope4 ,there 
is seen a long oval or lenticular spot  
of light1 very bright near the centre1  
especially with low powers4 ,but there  
is a want of the interest attaching to  
the strange figure of the ,great ,orion 
nebula4 ,the ,andromeda nebula has been 
partially resolved by ,lord ,rosse's    
great reflector1 and 7it is said7 more  
satisfactorily by the great refractor of
 ,harvard ,college4 ,in the             
spectroscope1 ,mr4 ,huggins informs us1 

the spectrum is peculiar4 ,continuous   
from the blue to the orange1 the light  
there appears to cease very abruptly2   
there is no indication of gaseity4      
,lastly1 the observer may turn to the   
pair ,mizar and ,alcor1 the former the  
middle star in the ,great ,bear's tail1 
the latter #ae' off4 ,it seems quite    
clear1 by the way1 that ,alcor has      
increased in brilliancy of late1 since  
among the ,arabians it was considered an
 evidence of very good eyesight to      
detect ,alcor1 whereas this star may now
 be easily seen even in nearly full     
moonlight4 ,mizar is a double star1 and 
a fourth star is seen in the same field 
of view with the others 7see ,plate #e74
 ,the distance between ,mizar and its   
companion is #add2 the magnitude of     
,mizar #c1 of the companion #e2 their   
colours white and pale green1           
respectively4     ,,chapter ,v4  ,a     
,,half-,,hour ,,with ,,andromeda1       
,,cygnus1 ,,etc4   ,our last half-hour  
with the double stars1 c41 must be a    

short one1 as we have already nearly    
filled the space allotted to these      
objects4 ,the observations now to be    
made are supposed to take place during  
the fourth quarter of the year1--at ten 
o'clock on ,october #bcrd2 or at nine on
 ,november #gth2 or at eight on         
,november #bbnd2 or at seven on         
,december #fth2 or at hours intermediate
 to these on intermediate days4  ,we    
look first1 as in former cases1 for the 
,great ,bear1 now lying low down towards
 the north4 ,towards the north-east1 a  
few degrees easterly1 are the twin-stars
 ,castor and ,pollux1 in a vertical     
position1 ,castor uppermost4 ,above     
these1 a little towards the right1 we   
see the brilliant ,capella2 and between 
,capella and the zenith is seen the     
festoon of ,perseus4 ,cassiopeia lies   
near the zenith1 towards the north1 and 
the ,milky ,way extends from the eastern
 horizon across the zenith to the       
western horizon4 ,low down in the east  
is ,orion1 half risen above horizon4    

,turning to the south1 we see high up   
above the horizon the square of         
,pegasus4 ,low down towards the         
south-south-west is ,fomalhaut1 pointed 
to by beta and alpha ,pegasi4 ,towards  
the west1 about half-way between the    
zenith and the horizon1 is the noble    
cross in ,cygnus2 below which1 towards  
the left1 we see ,altair1 and his       
companions beta and gamma ,aquil3 while 
towards the right we see the brilliant  
,vega4  ,during this half-hour we shall 
not confine ourselves to any particular 
region of the heavens1 but sweep the    
most conveniently situated              
constellations4  ,illustration3 ,,plate 
,v4  ,first1 however1 we should         
recommend the observer to try and get a 
good view of the great nebula in        
,andromeda1 which is not conveniently   
situated for observation1 but is so high
 that after a little trouble the        
observer may expect a more distinct view
 than in the previous quarter4 ,he will 
see beta ,andromed towards the          

south-east1 about #ah from the zenith1  
mu and nu nearly in a line towards the  
zenith1 and the nebula about half-way   
between beta and the zenith4  ,with a   
similar object it will be well to take  
another view of the great cluster in    
,perseus1 about #ah from the zenith     
towards the east-north-east 7see the    
pointers gamma and delta ,cassiopei in  
,map #d1 ,frontispiece71 the cluster    
being between delta ,cassiopei and alpha
 ,persei4  ,not very far off is the     
wonderful variable ,algol1 now due east1
 and about #eh above the horizon4 ,the  
variability of this celebrated object   
was doubtless discovered in very ancient
 times1 since the name ,al-gol1 or the  
,demon seems to point to a knowledge of 
the peculiarity of this slowly winking  
eye4 ,to ,goodricke1 however1 is due the
 rediscovery of ,algol's variability4   
,the period of variation is #b;d4 #bj;h4
 #dhm42 during #b;h4 #adm4 ,algol       
appears of the second magnitude2 the    
remaining #f-c_/d hours are occupied by 

the gradual decline of the star to the  
fourth magnitude1 and its equally       
gradual return to the second4 ,it will  
be found easy to watch the variations of
 this singular object1 though1 of       
course1 many of the minima are attained 
in the daytime4 ,the following may help 
the observer3--  ,on ,october #hth1     
#ahfg1 at about half-past eleven in the 
evening1 ,i noticed that ,algol had     
reached its minimum of brilliancy4      
,hence the next minimum was attained at 
about a quarter-past eight on the       
evening of ,october #aath2 the next at  
about five on the evening of ,october   
#adth1 and so on4 ,now1 if this process 
be carried on1 it will be found that the
 next evening minimum occurred at about 
#aj;h4 7circiter7 on the evening of     
,october #cast1 the next at about #aa;h4
 #cjm4 on the evening of ,november      
#bjth4 ,thus at whatever hour any       
minimum occurs1 another occurs six weeks
 and a day later1 at about the same     
hour4 ,this would be exact enough if the

 period of variation were exactly #b;d4 
#bjm4 #dhs41 but the period is nearly a 
minute greater1 and as there are fifteen
 periods in six weeks and a day1 it     
results that there is a difference of   
about #acm4 in the time at which the    
successive recurrences at nearly the    
same hour take place4 ,hence we are able
 to draw up the two following ,tables1  
which will suffice to give all the      
minima conveniently observable during   
the next two years4 ,starting from a    
minimum at about #aa;h4 #dem4 on        
,november #bjth1 #ahfg1 and noticing    
that the next #dc-;day period 7with the 
#acm4 added7 gives us an observation at 
midnight on ,january #bnd1 #ahfh1 and   
that successive periods would make the  
hour later yet1 we take the minimum next
 after that of ,january #bnd1 viz4 that 
of ,january #eth1 #ahfh1 #h;h4 #dhm41   
and taking #dc-;day periods 7with #acm4 
added to each71 we get the series--     
h4  m4 ,jan4   #e1 #ahfh1   #h  #de     
,p4,m4 ,feb4  #ag1 ----1   #h  #eh ---- 

,mar4  #ca1 ----1   #i  #aa ---- ,may   
#ac1 ----1   #i  #bd ---- ,june  #be1   
----1   #i  #cg ---- ,aug4   #g1 ----1  
#i  #ej ---- ,sept4 #ai1 ----1  #aj   #c
 ---- ,nov4   #a  ----1  #aj  #af ----  
,dec4  #ad1 ----1  #aj  #bi ---- ,jan4  
#bf1 #ahfi1  #aj  #db ---- ,mar4  #aj1  
----1  #aj  #be ---- ,mar4  #ac1 ----1  
#g  #dc ----#g ,apr4  #be1 ----1   #g   
#ef ---- ,june   #g1 ----1   #h   #i    
---- ,july  #bj1 ----1   #h  #bb ----   
,sept4  #a1 ----1   #h  #ce ---- ,oct4  
#ad1 ----1   #h  #dh ---- ,nov4  #bf1   
----1   #i   #a ---- ,jan4   #h1 #ahgj1 
#i  #ad ---- ,feb4  #bj1 ----1   #i  #bg
 ----  ,from the minimum at about #aj   
,p4,m4 on ,october #cast1 #ahfg1 we get 
in like manner the series--             
h4  m4 ,dec4  #ac1 #ahfg1  #aj  #ac     
,p4,m4 ,jan4  #be1 #ahfh1  #aj  #bf ----
 ,mar4   #h1 ----1  #aj  #ci ---- ,apr4 
#bj1 ----1  #aj  #eb ---- ,june   #b1   
----1  #aa   #e ---- ,june   #e1 ----1  
#g  #ec ----#h ,july  #ah1 ----1   #h   
#f ---- ,aug4  #cj1 ----1   #h  #ai ----

 ,oct4  #ab1 ----1   #h  #cb ---- ,nov4 
#bd1 ----1   #h  #de ---- ,jan4   #f1   
#ahfi1   #h  #eh ---- ,feb4  #ah1 ----1 
#i  #aa ---- ,apr4   #b1 ----1   #i  #bd
 ---- ,may   #ae1 ----1   #i  #cg ----  
,june  #bg1 ----1   #i  #ej ---- ,aug4  
#i1 ----1  #aj   #c ---- ,sept4 #ba1    
----1  #aj  #af ---- ,nov4   #c1 ----1  
#aj  #bi ---- ,dec4  #af1 ----1  #aj    
#db ---- ,jan4  #bh1 #ahgj1  #aj  #ee   
----  ,from one or other of these tables
 every observable minimum can be        
obtained4 ,thus1 suppose the observer   
wants to look for a minimum during the  
last fortnight in ,august1 #ahfh4 ,the  
first table gives him no information1   
the latter gives him a minimum at #h;h4 
#aim4 ,p4,m4 on ,august #cj2 hence of   
course there is a minimum at #aa;h4     
#cam4 ,p4,m4 on ,august #bg2 and there  
are no other conveniently observable    
minima during the fortnight in question4
  ,the cause of the remarkable variation
 in this star's brilliancy has been     
assigned by some astronomers to the     

presence of an opaque secondary1 which  
transits ,algol at regular intervals2   
others have adopted the view that ,algol
 is a luminous secondary1 revolving     
around an opaque primary4 ,of these     
views the former seems the most natural 
and satisfactory4 ,it points to a       
secondary whose mass bears a far greater
 proportion to that of the primary1 than
 the mass even of ,jupiter bears to the 
sun2 the shortness of the period is also
 remarkable4 ,it may be noticed that    
observation points to a gradual         
diminution in the period of ,algol's    
variation1 and the diminution seems to  
be proceeding more and more rapidly4    
,hence 7assuming the existence of a dark
 secondary7 we must suppose that either 
it travels in a resisting medium which  
is gradually destroying its motion1 or  
that there are other dependent orbs     
whose attractions affect the period of  
this secondary4 ,in the latter case the 
decrease in the period will attain a    
limit and be followed by an increase4   

,however1 interesting as the subject may
 be1 it is a digression from telescopic 
work1 to which we now return4  ,within  
the confines of the second map in ,plate
 #d is seen the fine star gamma         
,andromed4 ,at the hour of our          
observations it lies high up towards    
,e4,s4,e4 ,it is seen as a double star  
with very moderate telescopic power1 the
 distance between the components being  
upwards of #aj2 their magnitudes #c and 
#e-a_/b1 their colours orange and green4
 ,perhaps there is no more interesting  
double visible with low powers4 ,the    
smaller star is again double in         
first-class telescopes1 the components  
being yellow and blue according to some 
observers1 but according to others1 both
 green4  ,below gamma ,andromed lie the 
stars beta and gamma ,triangulorum1     
gamma a fine naked-eye triple 7the      
companions being delta and eta          
,triangulorum71 a fine object with a    
very low power4 ,to the right is alpha  
,triangulorum1 certainly less brilliant 

than beta4 ,below alpha are the three   
stars alpha1 beta1 and gamma ,arietis1  
the first an unequal and difficult      
double1 the companion being purple1 and 
only just visible 7under favourable     
circumstances7 with a good #c-;inch     
telescope2 the last an easy double1     
interesting as being the first ever     
discovered 7by ,hook1 in #affd71 the    
colours of components white and grey4   
,immediately below alpha ,arietis is the
 star alpha ,ceti1 towards the right of 
which 7a little lower7 is ,mira1 a      
wonderful variable4 ,this star has a    
period of #cca-a_/c days2 during a      
fortnight it appears as a star of the   
#bnd magnitude1--on each side of this   
fortnight there is a period of three    
months during one of which the star is  
increasing1 while during the other it is
 diminishing in brightness3 during the  
remaining five months of the period the 
star is invisible to the naked eye4     
,there are many peculiarities and       
changes in the variation of this star1  

into which space will not permit me to  
enter4  ,immediately above ,mira is the 
star alpha ,piscium at the knot of the  
,fishes' connecting band4 ,this is a    
fine double1 the distance between the   
components being about #c-a_/b1 their   
magnitudes #e and #f1 their colours pale
 green and blue 7see ,plate #e74  ,close
 to gamma ,aquarii 7see ,frontispiece1  
,map #d71 above and to the left of it1  
is the interesting double zeta ,aquarii2
 the distance between the components is 
about #c-a_/b1 their magnitudes #d and  
#d-a_/b1 both whitish yellow4 ,the      
period of this binary seems to be about 
#gej years4  ,turning next towards the  
south-west we see the second-magnitude  
star epsilon ,pegasi1 some #dj above the
 horizon4 ,this star is a wide but not  
easy double1 the secondary being only of
 the ninth magnitude2 its colour is     
lilac1 that of the primary being yellow4
  ,towards the right of epsilon ,pegasi 
and lower down are seen the three       
fourth-magnitude stars which mark the   

constellation ,equuleus4 ,of these the  
lowest is alpha1 to the right of which  
lies epsilon ,equulei1 a fifth-magnitude
 star1 really triple1 but seen as a     
double star with ordinary telescopes    
7,plate #e74 ,the distance between the  
components is nearly #aa1 their colours 
white and blue1 their magnitudes #e-a_/b
 and #g-a_/b4 ,the primary is a very    
close double1 which appears1 however1 to
 be opening out rather rapidly4         
,immediately below ,equuleus are the    
stars alpha#a and alpha#b ,capricorni1  
seen as a naked-eye double to the right 
of and above beta4 ,both alpha#a and    
alpha#b are yellow2 alpha#b is of the   
#crd1 alpha#a of the #dth magnitude2 in 
a good telescope five stars are seen1   
the other three being blue1             
ash-coloured1 and lilac4 ,the star beta 
,capricorni is also a wide double1 the  
components yellow and blue1 with many   
telescopic companions4  ,to the right of
 ,equuleus1 towards the west-south-west 
is the constellation ,delphinus4 ,the   

upper left-hand star of the rhombus of  
stars forming the head of the ,delphinus
 is the star gamma ,delphini1 a rather  
easy double 7see ,plate #e71 the        
components being nearly #ab apart1 their
 magnitudes #d and #g1 their colours    
golden yellow and flushed grey4  ,turn  
we next to the charming double ,albireo1
 on the beak of ,cygnus1 about #cf above
 the horizon towards the west4 ,the     
components are #cd-a_/b apart1 their    
magnitudes #c and #f1 their colours     
orange-yellow1 and blue4 ,it has been   
supposed 7perhaps on insufficient       
evidence7 that this star is merely an   
optical double4 ,it must always be      
remembered that a certain proportion of 
stars 7amongst those separated by so    
considerable a distance7 must be        
optically combined only4  ,the star chi 
,cygni is a wide double 7variable7 star4
 ,the components are separated by nearly
 #bf1 their magnitudes #e and #i1 their 
colours yellow and light blue4 chi may  
be found by noticing that there is a    

cluster of small stars in the middle of 
the triangle formed by the stars gamma1 
delta1 and beta ,cygni 7see ,map #d1    
,frontispiece71 and that chi is the     
nearest star of the cluster to beta4    
,the star phi ,cygni1 which is just     
above and very close to beta 7,albireo71
 does not belong to the cluster4 chi is 
about half as far again from phi as phi 
from ,albireo4 ,but as chi descends to  
the #aath magnitude at its minimum the  
observer must not always expect to find 
it very easily4 ,it has been known to be
 invisible at the epoch when it should  
have been most conspicuous4 ,the period 
of this variable is #djf days4  ,the    
star #fa ,cygni is an interesting one4  
,so far as observation has yet extended1
 it would seem to be the nearest to us  
of all stars visible in the northern    
hemisphere4 ,it is a fine double1 the   
components nearly equal 7#e-a_/b and    
#f71 both yellow1 and nearly #ai apart4 
,the period of this binary appears to be
 about #edj years4 ,to find #fa ,cygni  

note that epsilon and delta ,cygni form 
the diameter of a semicircle divided    
into two quadrants by alpha ,cygni      
7,arided74 ,on this semicircle1 on      
either side of alpha1 lie the stars nu  
and alpha ,cygni1 nu towards epsilon4   
,now a line from alpha to nu produced   
passes very near to #fa ,cygni at a     
distance from nu somewhat greater than  
half the distance of nu from alpha4     
,the star mu ,cygni lies in a corner of 
the constellation1 rather farther from  
zeta than zeta from epsilon ,cygni4 ,a  
line from epsilon to zeta produced meets
 kappa ,pegasi1 a fourth-magnitude star2
 and mu ,cygni1 a fifth-magnitude star1 
lies close above kappa ,pegasi4 ,the    
distance between the components is about
 #e-a_/b1 their magnitudes #e and #f1   
their colours white and pale blue4  ,the
 star psi ,cygni may next be looked for1
 but for this a good map of ,cygnus will
 be wanted1 as psi is not pointed to by 
any well-marked stars4 ,a line from     
alpha1 parallel to the line joining     

gamma and delta1 and about one-third    
longer than that line1 would about mark 
the position of psi ,cygni4 ,the        
distance between the components of this 
double is about #c-a_/b1 their          
magnitudes #e-a_/b and #h1 their colours
 white and lilac4  ,lastly1 the observer
 may turn to the stars gamma#a and      
gamma#b ,draconis towards the north-west
 about #dj above the horizon 7they are  
included in the second map of ,plate    
#b74 ,they form a wide double1 having   
equal 7fifth-magnitude7 components1 both
 grey4 7,see ,plate #e47     ,,chapter  
,,vi4  ,,half-,,hours ,,with ,,the      
,,planets4   ,in observing the stars1 we
 can select a part of the heavens which 
may be conveniently observed2 and in    
this way in the course of a year we can 
observe every part of the heavens       
visible in our northern hemisphere4 ,but
 with the planets the case is not quite 
so simple4 ,they come into view at no   
fixed season of the year3 some of them  
can never be seen by night on the       

meridian2 and they all shift their place
 among the stars1 so that we require    
some method of determining where to look
 for them on any particular night1 and  
of recognising them from neighbouring   
fixed stars4  ,the regular observer will
 of course make use of the ',nautical   
,almanac'2 but ',dietrichsen and        
,hannay's ,almanac' will serve every    
purpose of the amateur telescopist4 ,i  
will briefly describe those parts of the
 almanac which are useful to the        
observer4  ,it will be found that three 
pages are assigned to each month1 each  
page giving different information4 ,if  
we call these pages ,i4 ,,ii4 ,,iii41   
then in order that page ,i4 for each    
month may fall to the left of the open  
double page1 and also that ,i4 and ,,ii4
 may be open together1 the pages are    
arranged in the following order3 ,i4    
,,ii4 ,,iii42 ,,iii4 ,i4 ,,ii42 ,i4     
,,ii4 ,,iii42 and so on4  ,now page     
,,iii4 for any month does not concern   
the amateur observer4 ,it gives         

information concerning the moon's       
motions1 which is valuable to the       
sailor1 and interesting to the student  
of astronomy1 but not applicable to     
amateur observation4  ,illustration3    
,,plate ,,vi4  ,we have then only pages 
,i4 and ,,ii4 to consider3--  ,across   
the top of both pages the right         
ascension and declination of the planets
 ,venus1 ,jupiter1 ,mars1 ,saturn1      
,mercury1 and ,uranus are given1        
accompanied by those of two conspicuous 
stars4 ,this information is very        
valuable to the telescopist4 ,in the    
first place1 as we shall presently see1 
it shows him what planets are well      
situated for observation1 and secondly  
it enables him to map down the path of  
any planet from day to day among the    
fixed stars4 ,this is a very useful     
exercise1 by the way1 and also a very   
instructive one4 ,the student may either
 make use of the regular maps and mark  
down the planet's path in pencil1 taking
 a light curve through the points given 

by the data in his almanac1 or he may   
lay down a set of meridians suited to   
the part of the heavens traversed by the
 planet1 and then proceed to mark in the
 planet's path and the stars1 taking the
 latter either from his maps or from a  
convenient list of stars4#i ,my         
',handbook of the ,stars' has been      
constructed to aid the student in these 
processes4 ,it must be noticed that old 
maps are not suited for the work1       
because1 through precession1 the stars  
are all out of place as respects ,r4,a4 
and ,dec4 ,even the ,society's maps1    
constructed so as to be right for #ahcj1
 are beginning to be out of date4 ,but a
 matter of #bj or #cj years either way  
is not important4#aj ,my ,maps1         
,handbook and ,zodiac-chart have been   
constructed for the year #ahhj1 so as to
 be serviceable for the next fifty years
 or so4  ,next1 below the table of the  
planets1 we have a set of vertical      
columns4 ,these are1 in order1 the days 
of the month1 the calendar--in which are

 included some astronomical notices1    
amongst others the diameter of ,saturn  
on different dates1 the hours at which  
the sun rises and sets1 the sun's right 
ascension1 declination1 diameter1 and   
longitude2 then eight columns which do  
not concern the observer2 after which   
come the hours at which the moon rises  
and sets1 the moon's age2 and lastly 7so
 far as the observer is concerned7 an   
important column about ,jupiter's system
 of satellites4  ,next1 we have1 at the 
foot of the first page1 the hours at    
which the planets rise1 south1 and set2 
and at the foot of the second page we   
have the dates of conjunctions1         
oppositions1 and of other phenomena1 the
 diameters of ,venus1 ,jupiter1 ,mars1  
and ,mercury1 and finally a few words   
respecting the visibility of these four 
planets4  ,after the thirty-six pages   
assigned to the months follow four 7pp4 
#db-df7 in which much important         
astronomical information is contained2  
but the points which most concern our   

observer are 7i47 a small table showing 
the appearance of ,saturn's rings1 and  
7ii47 a table giving the hours at which 
,jupiter's satellites are occulted or   
eclipsed1 re-appear1 c4  ,we will now   
take the planets in the order of their  
distance from the sun3 we shall see that
 the information given by the almanac is
 very important to the observer4        
,mercury is so close to the sun as to be
 rarely seen with the naked eye1 since  
he never sets much more than two hours  
and a few minutes after the sun1 or     
rises by more than that interval before 
the sun4 ,it must not be supposed that  
at each successive epoch of most        
favourable appearance ,mercury sets so  
long after the sun or rises so long     
before him4 ,it would occupy too much of
 our space to enter into the            
circumstances which affect the length of
 these intervals4 ,the question1 in     
fact1 is not a very simple one4 ,all the
 necessary information is given in the  
almanac4 ,we merely notice that the     

planet is most favourably seen as an    
evening star in spring1 and as a morning
 star in autumn4#aa  ,the observer with 
an equatorial has of course no          
difficulty in finding ,mercury1 since he
 can at once direct his telescope to the
 proper point of the heavens4 ,but the  
observer with an alt-azimuth might fail 
for years together in obtaining a sight 
of this interesting planet1 if he       
trusted to unaided naked-eye            
observations in looking for him4        
,copernicus never saw ,mercury1 though  
he often looked for him2 and ,mr4 ,hind 
tells me he has seen the planet but once
 with the naked eye--though this perhaps
 is not a very remarkable circumstance1 
since the systematic worker in an       
observatory seldom has occasion to      
observe objects with the unaided eye4   
,by the following method the observer   
can easily pick up the planet4  ,across 
two uprights 7,fig4 #aj7 nail a straight
 rod1 so that when looked at from some  
fixed point of view the rod may         

correspond to the sun's path near the   
time of observation4 ,the rod should be 
at right-angles to the line of sight to 
its centre4 ,fasten another rod at right
 angles to the first4 ,from the point at
 which the rods cross measure off and   
mark on both rods spaces each subtending
 a degree as seen from the point of     
view4 ,thus1 if the point of view is    
#i-a_/b feet off1 these spaces must each
 be #b inches long1 and they must be    
proportionately less or greater as the  
eye is nearer or farther4               
,illustration3 ,fig4 #aj4  ,now suppose 
the observer wishes to view ,mercury on 
some day1 whereon ,mercury is an evening
 star4 ,take1 for instance1 ,june #ith1 
#ahfh4 ,we find from ',dietrichsen' that
 on this day 7at noon7 ,mercury's ,r4,a4
 is #f;h4 #ecm4 #bcs43 and the sun's    
#e;h4 #aam4 #cas4 ,we need not trouble  
ourselves about the odd hours after     
noon1 and thus we have ,mercury's ,r4,a4
 greater than the sun's by #a;h4 #dam4  
#ebs4 ,now we will suppose that the     

observer has so fixed his uprights and  
the two rods1 that the sun1 seen from   
the fixed point of view1 appears to pass
 the point of crossing of the rods at   
half-past seven1 then ,mercury will pass
 the cross-rod at #aam4 #ebs4 past nine4
 ,but where8 ,to learn this we must take
 out ,mercury's declination1 which is   
#bd #dc' #ah ,n41 and the sun's1 which  
is #bb #ei' #aj ,n4 ,the difference1 #a 
#dd' #h ,n4 gives us ,mercury's place1  
which it appears is rather less than    
#a-c_/d degree north of the sun4 ,thus1 
about #a;h4 #dbm4 after the sun has     
passed the cross-rod1 ,mercury will pass
 it between the first and second        
divisions above the point of fastening4 
,the sun will have set about an hour1   
and ,mercury will be easily found when  
the telescope is directed towards the   
place indicated4  ,it will be noticed   
that this method does not require the   
time to be exactly known4 ,all we have  
to do is to note the moment at which the
 sun passes the point of fastening of   

the two rods1 and to take our #a;h4     
#dbm4 from that moment4  ,this method1  
it may be noticed in passing1 may be    
applied to give naked-eye observations  
of ,mercury at proper seasons 7given in 
the almanac74 ,by a little ingenuity it 
may be applied as well to morning as to 
evening observations1 the sun's passage 
of the cross-rod being taken on one     
morning and ,mercury's on the next1 so  
many minutes before the hour of the     
first observation4 ,in this way several 
views of ,mercury may be obtained during
 the year4  ,such methods may appear    
very insignificant to the systematic    
observer with the equatorial1 but that  
they are effective ,i can assert from my
 own experience4 ,similar methods may be
 applied to determine from the position 
of a known object1 that of any          
neighbouring unknown object even at     
night4 ,the cross-rod must be shifted   
7or else two cross-rods used7 when the  
unknown precedes the known object4 ,if  
two cross-rods are used1 account must be

 taken of the gradual diminution in the 
length of a degree of right ascension as
 we leave the equator4  ,even simpler   
methods carefully applied may serve to  
give a view of ,mercury4 ,to show this1 
,i may describe how ,i obtained my first
 view of this planet4 ,on ,june #ast1   
#ahfc1 ,i noticed1 that at five minutes 
past seven the sun1 as seen from my     
study window1 appeared from behind the  
gable-end of ,mr4 ,st4 ,aubyn's house at
 ,stoke1 ,devon4 ,i estimated the effect
 of ,mercury's northerly declination    
7different of course for a vertical     
wall1 than for the cross-rod in fig4 #h1
 which1 in fact1 agrees with a          
declination-circle71 and found that he  
would pass out opposite a particular    
point of the wall a certain time after  
the sun4 ,i then turned the telescope   
towards that point1 and focussed for    
distinct vision of distant objects1 so  
that the outline of the house was seen  
out of focus4 ,as the calculated time of
 apparition approached1 ,i moved the    

telescope up and down so that the field 
swept the neighbourhood of the estimated
 point of apparition4 ,i need hardly say
 that ,mercury did not appear exactly at
 the assigned point1 nor did ,i see him 
make his first appearance2 but ,i picked
 him up so soon after emergence that the
 outline of the house was in the field  
of view with him4 ,he appeared as a     
half-disc4 ,i followed him with the     
telescope until the sun had set1 and    
soon after ,i was able to see him very  
distinctly with the naked eye4 ,he shone
 with a peculiar brilliance on the still
 bright sky2 but although perfectly     
distinct to the view when his place was 
indicated1 he escaped detection by the  
undirected eye4#ab  ,mercury does not   
present any features of great interest  
in ordinary telescopes2 though he       
usually appears better defined than     
,venus1 at least as the latter is seen  
on a dark sky4 ,the phases are          
pleasingly seen 7as shown in ,plate #f7 
with a telescope of moderate power4 ,for

 their proper observation1 however1 the 
planet must be looked for with the      
telescope in the manner above indicated1
 as he always shows a nearly            
semi-circular disc when he is visible to
 the naked eye4  ,we come next to       
,venus1 the most splendid of all the    
planets to the eye4 ,in the telescope   
,venus disappoints the observer1        
however4 ,her intense lustre brings out 
every defect of the instrument1 and     
especially the chromatic aberration4 ,a 
dark glass often improves the view1 but 
not always4 ,besides1 an interposed     
glass has an unpleasant effect on the   
field of view4  ,perhaps the best method
 of observing ,venus is to search for   
her when she is still high above the    
horizon1 and when therefore the         
background of the sky is bright enough  
to take off the planet's glare4 ,the    
method ,i have described for the        
observation of ,mercury will prove very 
useful in the search for ,venus when the
 sun is above the horizon or but just   

set4 ,of course1 when an object is to be
 looked for high above the horizon1 the 
two rods which support the cross-rods   
must not be upright1 but square to the  
line of view to that part of the sky4   
,but the observer must not expect to see
 much during his observation of ,venus4 
,in fact1 he can scarcely do more than  
note her varying phases 7see ,plate #f7 
and the somewhat uneven boundary of the 
terminator4 ,our leading observers have 
done so little with this fascinating but
 disappointing planet1 that amateurs    
must not be surprised at their own      
failure4  ,i suppose the question       
whether ,venus has a satellite1 or at   
any rate whether the object supposed to 
have been seen by ,cassini and other old
 observers were a satellite1 must be    
considered as decided in the negative4  
,that ,cassini should have seen an      
object which ,dawes and ,webb have      
failed to see must be considered utterly
 improbable4  ,leaving the inferior     
planets1 we come to a series of         

important and interesting objects4      
,first we have the planet ,mars1 nearly 
the last in the scale of planetary      
magnitude1 but far from being the least 
interesting of the planets4 ,it is in   
fact quite certain that we obtain a     
better view of ,mars than of any object 
in the heavens1 save the ,moon alone4   
,he may present a less distinguished    
appearance than ,jupiter or ,saturn1 but
 we see his surface on a larger scale   
than that of either of those giant orbs1
 even if we assume that we ever obtain a
 fair view of their real surface4  ,nor 
need the moderately armed observer      
despair of obtaining interesting views  
of ,mars4 ,the telescope with which     
,beer and ,mdler made their celebrated  
series of views was only a #d-;inch one1
 so that with a #c-;inch or even a      
#b-;inch aperture the attentive observer
 may expect interesting views4 ,in fact1
 more depends on the observer than on   
the instrument4 ,a patient and attentive
 scrutiny will reveal features which at 

the first view wholly escape notice4    
,in ,plate #f ,i have given a series of 
views of ,mars much more distinct than  
an observer may expect to obtain with   
moderate powers4 ,i add a chart of      
,mars1 a miniature of one ,i have       
prepared from a charming series of      
tracings supplied me by ,mr4 ,dawes4    
,the views taken by this celebrated     
observer in #aheb1 #ahef1 #ahfj1 #ahfb1 
and #ahfd1 are far better than any      
others ,i have seen4 ,the views by ,beer
 and ,mdler are good1 as are some of    
,secchi's 7though they appear badly     
drawn71 ,nasmyth's and ,phillips'2      
,delarue's two views are also admirable2
 and ,lockyer has given a better set of 
views than any of the others4 ,but there
 is an amount of detail in ,mr4 ,dawes' 
views which renders them superior to any
 yet taken4 ,i must confess ,i failed at
 a first view to see the full value of  
,mr4 ,dawes' tracings4 ,faint marks     
appeared1 which ,i supposed to be merely
 intended to represent shadings scarcely

 seen4 ,a more careful study shewed me  
that every mark is to be taken as the   
representative of what ,mr4 ,dawes      
actually saw4 ,the consistency of the   
views is perfectly wonderful1 when      
compared with the vagueness and         
inconsistency observable in nearly all  
other views4 ,and this consistency is   
not shown by mere resemblance1 which    
might have been an effect rather of     
memory 7unconsciously exerted7 than     
observation4 ,the same feature changes  
so much in figure1 as it appears on     
different parts of the disc1 that it was
 sometimes only on a careful projection 
of different views that ,i could        
determine what certain features near the
 limb represented4 ,but when this had   
been done1 and the distortion through   
the effect of foreshortening corrected1 
the feature was found to be as true in  
shape as if it had been seen in the     
centre of the planet's disc4  ,in       
examining ,mr4 ,dawes' drawings it was  
necessary that the position of ,mars'   

axis should be known4 ,the data for     
determining this were taken from ,dr4   
,oudemann's determinations given in a   
valuable paper on ,mars issued from ,mr4
 ,bishop's observatory4 ,but instead of 
calculating ,mars' presentation by the  
formul there given1 ,i found it         
convenient rather to make use of        
geometrical constructions applied to my 
',charts of the ,terrestrial ,planets4' 
,taking ,mdler's start-point for        
,martial longitudes1 that is the        
longitude-line passing near ,dawes'     
forked bay1 ,i found that my results    
agreed pretty fairly with those in      
,prof4 ,phillips' map1 so far as the    
latter went2 but there are many details 
in my charts not found in ,prof4        
,phillips' nor in ,mdler's earlier      
charts4  ,i have applied to the         
different features the names of those   
observers who have studied the physical 
peculiarities presented by ,mars4 ,mr4  
,dawes' name naturally occurs more      
frequently than others4 ,indeed1 if ,i  

had followed the rule of giving to each 
feature the name of its discoverer1 ,mr4
 ,dawes' name would have occurred much  
more frequently than it actually does4  
,on account of the eccentricity of his  
orbit1 ,mars is seen much better in some
 oppositions than in others4 ,when best 
seen the southern hemisphere is brought 
more into view than the northern because
 the summer of his northern hemisphere  
occurs when he is nearly in aphelion 7as
 is the case with the ,earth by the     
way74  ,the relative dimensions and     
presentation of ,mars1 as seen in       
opposition in perihelion1 and in        
opposition in aphelion1 are shown in the
 two rows of figures4  ,in and near     
quadrature ,mars is perceptibly gibbous4
 ,he is seen thus about two months      
before or after opposition4 ,in the     
former case1 he rises late and comes to 
the meridian six hours or so after      
midnight4 ,in the latter case1 he is    
well seen in the evening1 coming to the 
meridian at six4 ,his appearance and    

relative dimensions as he passes from   
opposition to quadrature are shown in   
the last three figures of the upper row4
  ,mars' polar caps may be seen with    
very moderate powers4  ,i add four sets 
of meridians 7,plate #f71 by filling in 
which from the charts the observer may  
obtain any number of views of the planet
 as it appears at different times4      
,passing over the asteroids1 which are  
not very interesting objects to the     
amateur telescopist1 we come to         
,jupiter1 the giant of the solar system1
 surpassing our ,earth more than #adjj  
times in volume1 and overweighing all   
the planets taken together twice over4  
,jupiter is one of the easiest of all   
objects of telescopic observation4 ,no  
one can mistake this orb when it shines 
on a dark sky1 and only ,venus can be   
mistaken for it when seen as a morning  
or evening star4 ,sometimes both are    
seen together on the twilight sky1 and  
then ,venus is generally the brighter4  
,seen1 however1 at her brightest and at 

her greatest elongation from the sun1   
her splendour scarcely exceeds that with
 which ,jupiter shines when high above  
the southern horizon at midnight4       
,jupiter's satellites may be seen with  
very low powers2 indeed the outer ones  
have been seen with the naked eye1 and  
all are visible in a good opera-glass4  
,their dimensions relatively to the disc
 are shown in ,plate #g4 ,their greatest
 elongations are compared with the disc 
in the low-power view4  ,jupiter's belts
 may also be well seen with moderate    
telescopic power4 ,the outer parts of   
his disc are perceptibly less bright    
than the centre4  ,more difficult of    
observation are the transits of the     
satellites and of their shadows4 ,still 
the attentive observer can see the      
shadows with an aperture of two inches1 
and the satellites themselves with an   
aperture of three inches4  ,the minute  
at which the satellites enter on the    
disc1 or pass off1 is given in          
',dietrichsen's ,almanac4' ,the         

',nautical ,almanac' also gives the     
corresponding data for the shadows4     
,the eclipses of the satellites in      
,jupiter's shadow1 and their            
occultations by his disc1 are also given
 in ',dietrichsen's ,almanac4'  ,in the 
inverting telescope the satellites move 
from right to left in the nearer parts  
of their orbit1 and therefore transit   
,jupiter's disc in that direction1 and  
from left to right in the farther parts4
 ,also note that before opposition1 7i47
 the shadows travel in front of the     
satellites in transiting the disc2 7ii47
 the satellites are eclipsed in         
,jupiter's shadow2 7iii47 they reappear 
from behind his disc4 ,on the other     
hand1 after opposition1 7i47 the shadows
 travel behind the satellites in        
transiting the disc2 7ii47 the          
satellites are occulted by the disc2    
7iii47 they reappear from eclipse in    
,jupiter's shadow4  ,conjunctions of the
 satellites are common phenomena1 and   
may be waited for by the observer who   

sees the chance4 ,an eclipse of one     
satellite by the shadow of another is   
not a common phenomenon2 in fact1 ,i    
have never heard of such an eclipse     
being seen4 ,that a satellite should be 
quite extinguished by another's shadow  
is a phenomenon not absolutely          
impossible1 but which cannot happen save
 at long intervals4  ,the shadows are   
not black spots as is erroneously stated
 in nearly all popular works on         
astronomy4 ,the shadow of the fourth1   
for instance1 is nearly all penumbra1   
the really black part being quite minute
 by comparison4 ,the shadow of the third
 has a considerable penumbra1 and even  
that of the first is not wholly black4  
,these penumbras may not be perceptible1
 but they affect the appearance of the  
shadows4 ,for instance1 the shadow of   
the fourth is perceptibly larger but    
less black than that of the third1      
though the third is the larger          
satellite4  ,in transit the first       
satellite moves fastest1 the fourth     

slowest1 the others in their order4 ,the
 shadow moves just as fast 7appreciably7
 as the satellite it belongs to4        
,sometimes the shadow of the satellite  
may be seen to overtake 7apparently7 the
 disc of another4 ,in such a case the   
shadow does not pass over the disc1 but 
the disc conceals the shadow4 ,this is  
explained by the fact that the shadow1  
if visible throughout its length1 would 
be a line reaching slantwise from the   
satellite it belongs to1 and the end of 
the shadow 7that is1 the point where it 
meets the disc7 is not the point where  
the shadow crosses the orbit of any     
inner satellite4 ,thus the latter may be
 interposed between the end of the      
shadow--the only part of the shadow     
really visible--and the eye2 but the end
 of the shadow cannot be interposed     
between the satellite and the eye4 ,if a
 satellite on the disc were eclipsed by 
another satellite1 the black spot thus  
formed would be in another place from   
the black spot on the planet's body4 ,i 

mention all this because1 simple as the 
question may seem1 ,i have known careful
 observers to make mistakes on this     
subject4 ,a shadow is seen crossing the 
disc and overtaking1 apparently1 a      
satellite in transit4 ,it seems         
therefore1 on a first view1 that the    
shadow will hide the satellite1 and     
observers have even said that they have 
seen this happen4 ,but they are         
deceived4 ,it is obvious that if one    
satellite eclipse another1 the shadows  
of both must occupy the same point on   
,jupiter's body4 ,thus it is the        
overtaking of one shadow by another on  
the disc1 and not the overtaking of a   
satellite by a shadow1 which determines 
the occurrence of that as yet unrecorded
 phenomenon1 the eclipse of one         
satellite by another4#ac  ,the          
satellites when far from ,jupiter seem  
to lie in a straight line through his   
centre4 ,but as a matter of fact they do
 not in general lie in an exact straight
 line4 ,if their orbits could be seen as

 lines of light1 they would appear1 in  
general1 as very long ellipses4 ,the    
orbit of the fourth would frequently be 
seen to be quite clear of ,jupiter's    
disc1 and the orbit of the third might  
in some very exceptional instances pass 
just clear of the disc4 ,the satellites 
move most nearly in a straight line     
7apparently7 when ,jupiter comes to     
opposition in the beginning of ,february
 or ,august1 and they appear to depart  
most from rectilinear motion when       
opposition occurs in the beginning of   
,may and ,november4 ,at these epochs the
 fourth satellite may be seen to pass   
above and below ,jupiter's disc at a    
distance equal to about one-sixth of the
 disc's radius4  ,the shadows do not    
travel in the same apparent paths as the
 satellites themselves across the disc1 
but 7in an inverting telescope7 below   
from ,august to ,january1 and above from
 ,february to ,july4  ,we come now to   
the most charming telescopic object in  
the heavens--the planet ,saturn4        

,inferior only to ,jupiter in mass and  
volume1 this planet surpasses him in the
 magnificence of his system4 ,seen in a 
telescope of adequate power1 ,saturn is 
an object of surpassing loveliness4 ,he 
must be an unimaginative man who can see
 ,saturn for the first time in such a   
telescope1 without a feeling of awe and 
amazement4 ,if there is any object in   
the heavens--,i except not even the     
,sun--calculated to impress one with a  
sense of the wisdom and omnipotence of  
the ,creator it is this4 ,his fashioning
 hand is indeed visible throughout      
space1 but in ,saturn's system it is    
most impressively manifest4  ,saturn1 to
 be satisfactorily seen1 requires a much
 more powerful telescope than ,jupiter4 
,a good #b-;inch telescope will do much1
 however1 in exhibiting his rings and   
belts4 ,i have never seen him           
satisfactorily myself with such an      
aperture1 but ,mr4 ,grover has not only 
seen the above-named features1 but even 
a penumbra to the shadow on the rings   

with a #b-;inch telescope4  ,saturn     
revolving round the sun in a long       
period--nearly thirty years--presents   
slowly varying changes of appearance    
7see ,plate #g74 ,at one time the edge  
of his ring is turned nearly towards the
 earth2 seven or eight years later his  
rings are as much open as they can ever 
be2 then they gradually close up during 
a corresponding interval2 open out      
again1 exhibiting a different face2 and 
finally close up as first seen4 ,the    
last epoch of greatest opening occurred 
in #ahef1 the next occurs in #ahgj3 the 
last epoch of disappearance occurred in 
#ahfb-fc1 the next occurs in #ahgi4 ,the
 successive views obtained are as in    
,plate #g in order from right to left1  
then back to the right-hand figure 7but 
sloped the other way72 inverting the    
page we have this figure thus sloped1   
and the following changes are now       
indicated by the other figures in order 
back to the first 7but sloped the other 
way and still inverted71 thus returning 

to the right-hand figure as seen without
 inversion4  ,the division in the ring  
can be seen in a good #b-;inch aperture 
in favourable weather4 ,the dark ring   
requires a good #d-;inch and good       
weather4  ,saturn's satellites do not1  
like ,jupiter's1 form a system of nearly
 equal bodies4 ,titan1 the sixth1 is    
probably larger than any of ,jupiter's  
satellites4 ,the eighth also 7,japetus7 
is a large body1 probably at least equal
 to ,jupiter's third satellite4 ,but    
,rhea1 ,dione1 and ,tethys are much less
 conspicuous1 and the other three cannot
 be seen without more powerful          
telescopes than those we are here       
dealing with4  ,so far as my own        
experience goes1 ,i consider that the   
five larger satellites may be seen      
distinctly in good weather with a good  
#c-a_/b-;inch aperture4 ,i have never   
seen them with such an aperture1 but ,i 
judge from the distinctness with which  
these satellites may be seen with a     
#d-;inch aperture4 ,titan is generally  

to be looked for at a considerable      
distance from ,saturn--always when the  
ring is widely open4 ,japetus is to be  
looked for yet farther from the disc4   
,in fact1 when ,saturn comes to         
opposition in perihelion 7in winter only
 this can happen7 ,japetus may be as far
 from ,saturn as one-third of the       
apparent diameter of the moon4 ,i       
believe that under these circumstances1 
or even under less favourable           
circumstances1 ,japetus could be seen   
with a good opera-glass4 ,so also might 
,titan4  ,transits1 eclipses1 and       
occulations of ,saturn's satellites can 
only be seen when the ring is turned    
nearly edgewise towards the earth4 ,for 
the orbits of the seven inner satellites
 lying nearly in the plane of the rings 
would 7if visible throughout their      
extent7 then only appear as straight    
lines1 or as long ellipses cutting the  
planet's disc4  ,the belts on ,saturn   
are not very conspicuous4 ,a good       
#c-a_/b-;inch is required 7so far as my 

experience extends7 to show them        
satisfactorily4  ,the rings when turned 
edgewise either towards the earth or    
sun1 are not visible in ordinary        
telescopes1 neither can they be seen    
when the earth and sun are on opposite  
sides of the rings4 ,in powerful        
telescopes the rings seem never entirely
 to disappear4  ,the shadow of the      
planet on the rings may be well seen    
with a good #b-;inch telescope1 which   
will also show ,ball's division in the  
rings4 ,the shadow of the rings on the  
planet is a somewhat more difficult     
feature4 ,the shadow of the planet on   
the rings is best seen when the rings   
are well open and the planet is in or   
near quadrature4 ,it is to be looked for
 to the left of the ball 7in an         
inverting telescope7 at quadrature      
preceding opposition1 and to the right  
at quadrature following opposition4     
,saturn is more likely to be studied at 
the latter than at the former           
quadrature1 as in quadrature preceding  

opposition he is a morning star4 ,the   
shadow of the rings on the planet is    
best seen when the rings are but        
moderately open1 and ,saturn is in or   
near quadrature4 ,when the shadow lies  
outside the rings it is best seen1 as   
the dark ring takes off from the        
sharpness of the contrast when the      
shadow lies within the ring4 ,it would  
take more space than ,i can spare here  
to show how it is to be determined      
7independently7 whether the shadow lies 
within or without the ring4 ,but the    
',nautical ,almanac' gives the means of 
determining this point4 ,when1 in the   
table for assigning the appearance of   
the rings1 l is less than l' the shadow 
lies outside the ring1 when l is greater
 than l' the shadow lies within the     
ring4  ,uranus is just visible to the   
naked eye when he is in opposition1 and 
his place accurately known4 ,but he     
presents no phenomena of interest4 ,i   
have seen him under powers which made   
his disc nearly equal to that of the    

moon1 yet could see nothing but a faint 
bluish disc4  ,neptune also is easily   
found if his place be accurately noted  
on a map1 and a good finder used4 ,we   
have only to turn the telescope to a few
 stars seen in the finder nearly in the 
place marked in our map1 and presently  
we shall recognise the one we want by   
the peculiarity of its light4 ,what is  
the lowest power which will exhibit     
,neptune as a disc ,i do not know1 but  
,i am certain no observer can mistake   
him for a fixed star with a #b-;inch    
aperture and a few minutes' patient     
scrutiny in favourable weather4         
,illustration3 ,,plate ,,vii4           
,,chapter ,,vii4  ,,half-,,hours ,,with 
,,the ,,sun ,,and ,,moon4   ,the moon   
perhaps is the easiest of all objects of
 telescopic observation4 ,a very        
moderate telescope will show her most   
striking features1 while each increase  
of power is repaid by a view of new     
details4 ,yet in one sense the moon is a
 disappointing object even to the       

possessor of a first-class instrument4  
,for the most careful and persistent    
scrutiny1 carried on for a long series  
of years1 too often fails to reward the 
observer by any new discoveries of      
interest4 ,our observer must therefore  
rather be prepared to enjoy the         
observation of recognised features than 
expect to add by his labours to our     
knowledge of the earth's nearest        
neighbour4  ,although the moon is a     
pleasing and surprising telescopic      
object when full1 the most interesting  
views of her features are obtained at   
other seasons4 ,if we follow the moon as
 she waxes or wanes1 we see the true    
nature of that rough and bleak mountain 
scenery1 which when the moon is full is 
partially softened through the want of  
sharp contrasts of light and shadow4 ,if
 we watch1 even for half an hour only1  
the changing form of the ragged line    
separating light from darkness on the   
moon's disc1 we cannot fail to be       
interested4 ,the outlying and isolated  

peak of some great mountain-chain       
becomes gradually larger1 and is finally
 merged in the general luminous surface2
 great circular spaces1 enclosed with   
rough and rocky walls many miles in     
diameter1 become apparent2 some with    
flat and perfectly smooth floors1       
variegated with streaks2 others in which
 the flat floor is dotted with numerous 
pits or covered with broken fragments of
 rock4 ,occasionally a regularly-formed 
and unusually symmetrical circular      
formation makes its appearance2 the     
exterior surface of the wall bristling  
with terraces rising gradually from the 
plain1 the interior one much more steep1
 and instead of a flat floor1 the inner 
space is concave or cup-shaped1 with a  
solitary peak rising in the centre4     
,solitary peaks rise from the level     
plains and cast their long narrow       
shadows athwart the smooth surface4     
,vast plains of a dusky tint become     
visible1 not perfectly level1 but       
covered with ripples1 pits1 and         

projections4 ,circular wells1 which have
 no surrounding wall dip below the      
plain1 and are met with even in the     
interior of the circular mountains and  
on the tops of their walls4 ,from some  
of the mountains great streams of a     
brilliant white radiate in all          
directions and can be traced for        
hundreds of miles4 ,we see1 again1 great
 fissures1 almost perfectly straight and
 of great length1 although very narrow1 
which appear like the cracks in moist   
clayey soil when dried by the sun4#ad   
,but interesting as these views may be1 
it was not for such discoveries as these
 that astronomers examined the surface  
of the moon4 ,the examination of mere   
peculiarities of physical condition is1 
after all1 but barren labour1 if it lead
 to no discovery of physical variation4 
,the principal charm of astronomy1 as   
indeed of all observational science1    
lies in the study of change--of         
progress1 development1 and decay1 and   
specially of systematic variations      

taking place in regularly-recurring     
cycles4 ,and it is in this relation that
 the moon has been so disappointing an  
object of astronomical observation4 ,for
 two centuries and a half her face has  
been scanned with the closest possible  
scrutiny2 her features have been        
portrayed in elaborate maps2 many an    
astronomer has given a large portion of 
his life to the work of examining       
craters1 plains1 mountains1 and valleys1
 for the signs of change2 but until     
lately no certain evidence--or rather1  
no evidence save of the most doubtful   
character--has been afforded that the   
moon is other than a dead and useless   
waste of extinct volcanoes4 ,whether the
 examination of the remarkable spot     
called ,linn--where lately signs were   
supposed to have been seen of a process 
of volcanic eruption--will prove an     
exception to this rule1 remains to be   
seen4 ,the evidence seems to me strongly
 to favour the supposition of a change  
of some sort having taken place in this 

neighbourhood4  ,the sort of scrutiny   
required for the discovery of changes1  
or for the determination of their       
extent1 is far too close and laborious  
to be attractive to the general         
observer4 ,yet the kind of observation  
which avails best for the purpose is    
perhaps also the most interesting which 
he can apply to the lunar details4 ,the 
peculiarities presented by a spot upon  
the moon are to be observed from hour to
 hour 7or from day to day1 according to 
the size of the spot7 as the sun's light
 gradually sweeps across it1 until the  
spot is fully lighted2 then as the moon 
wanes and the sun's light gradually     
passes from the spot1 the series of     
observations is to be renewed4 ,a       
comparison of them is likely--especially
 if the observer is a good artist and   
has executed several faithful           
delineations of the region under        
observation1 to throw much light upon   
the real contour of the moon's surface  
at this point4  ,in the two lunar views 

in ,plate #g some of the peculiarities  
,i have described are illustrated4 ,but 
the patient observer will easily be able
 to construct for himself a set of      
interesting views of different regions4 
,it may be noticed that for observation 
of the waning moon there is no occasion 
to wait for those hours in which only   
the waning moon is visible during the   
night4 ,of course for the observation of
 a particular region under a particular 
illumination1 the observer has no choice
 as to hour4 ,but for generally         
interesting observations of the waning  
moon he can wait till morning and       
observe by daylight4 ,the moon is1 of   
course1 very easily found by the unaided
 eye 7in the day time7 when not very    
near to the sun2 and the methods        
described in ,chapter ,v4 will enable   
the observer to find the moon when she  
is so near to the sun as to present the 
narrowest possible sickle of light4     
,one of the most interesting features of
 the moon1 when she is observed with a  

good telescope1 is the variety of colour
 presented by different parts of her    
surface4 ,we see regions of the purest  
white--regions which one would be apt to
 speak of as snow-covered1 if one could 
conceive the possibility that snow      
should have fallen where 7now1 at least7
 there is neither air nor water4 ,then  
there are the so-called seas1 large grey
 or neutral-tinted regions1 differing   
from the former not merely in colour and
 in tone1 but in the photographic       
quality of the light they reflect       
towards the earth4 ,some of the seas    
exhibit a greenish tint1 as the ,sea of 
,serenity and the ,sea of ,humours4     
,where there is a central mountain      
within a circular depression1 the       
surrounding plain is generally of a     
bluish steel-grey colour4 ,there is a   
region called the ,marsh of ,sleep1     
which exhibits a pale red tint1 a colour
 seen also near the ,hyrcinian          
mountains1 within a circumvallation     
called ,lichtenburg4 ,the brightest     

portion of the whole lunar disc is      
,aristarchus1 the peaks of which shine  
often like stars1 when the mountain is  
within the unillumined portion of the   
moon4 ,the darkest regions are ,grimaldi
 and ,endymion and the great plain      
called ,plato by modern                 
astronomers--but1 by ,hevelius1 the     
,greater ,black ,lake4  ,the            
,sun4--,observation of the sun is       
perhaps on the whole the most           
interesting work to which the possessor 
of a moderately good telescope can apply
 his instrument4 ,those wonderful       
varieties in the appearance of the solar
 surface which have so long perplexed   
astronomers1 not only supply in         
themselves interesting subjects of      
observation and examination1 but gain an
 enhanced meaning from the consideration
 that they speak meaningly to us of the 
structure of an orb which is the source 
of light and heat enjoyed by a series of
 dependent worlds whereof our earth     
is--in size at least--a comparatively   

insignificant member4 ,swayed by the    
attraction of this giant globe1 ,jupiter
 and ,saturn1 ,uranus and ,neptune1 as  
well as the four minor planets1 and the 
host of asteroids1 sweep continuously in
 their appointed orbits1 in ever new but
 ever safe and orderly relations amongst
 each other4 ,if the sun's light and    
heat were lost1 all life and work among 
the denizens of these orbs would at once
 cease2 if his attractive energy were   
destroyed1 these orbs would cease to    
form a system4  ,the sun may be observed
 conveniently in many ways1 some more   
suited to the general observer who has  
not time or opportunity for systematic  
observation2 others more instructive1   
though involving more of preparation and
 arrangement4  ,the simplest method of  
observing the sun is to use the         
telescope in the ordinary manner1       
protecting the eye by means of          
dark-green or neutral-tinted glasses4   
,some of the most interesting views ,i  
have ever obtained of the sun1 have     

resulted from the use of the ordinary   
terrestrial or erecting eye-piece1      
capped with a dark glass4 ,the          
magnifying power of such an eye-piece   
is1 in general1 much lower than that    
available with astronomical eye-pieces4 
,but vision is very pleasant and        
distinct when the sun is thus observed1 
and a patient scrutiny reveals almost   
every feature which the highest         
astronomical power applicable could     
exhibit4 ,then1 owing to the greater    
number of intervening lenses1 there is  
not the same necessity for great        
darkness or thickness in the coloured   
glass1 so that the colours of the solar 
features are seen much more             
satisfactorily than when astronomical   
eye-pieces are employed4  ,in using     
astronomical eye-pieces it is convenient
 to have a rotating wheel attached1 by  
which darkening glasses of different    
power may be brought into use as the    
varying illumination may require4       
,those who wish to observe carefully and

 closely a minute portion of the solar  
disc1 should employ ,dawes' eye-piece3  
in this a metallic screen placed in the 
focus keeps away all light but such as  
passes through a minute hole in the     
diaphragm4  ,another convenient method  
of diminishing the light is to use a    
glass prism1 light being partially      
reflected from one of the exterior      
surfaces1 while the refracted portion is
 thrown out at another4  ,very beautiful
 and interesting views may be obtained  
by using such a pyramidal box as is     
depicted in fig4 #aa4  ,illustration3   
,fig4 #aa4  ,this box should be made of 
black cloth or calico fastened over a   
light framework of wire or cane4 ,the   
base of the pyramid should be covered on
 the inside with a sheet of white glazed
 paper1 or with some other uniform white
 surface4 ,captain ,noble1 ,i believe1  
makes use of a surface of plaster of    
,paris1 smoothed while wet with         
plate-glass4 ,the door b c enables the  
observer to change power without        

removing the box1 while larger doors1 d 
e and g f1 enable him to examine the    
image2 a dark cloth1 such as            
photographers use1 being employed1 if   
necessary1 to keep out extraneous light4
 ,the image may also be examined from   
without1 if the bottom of the pyramid be
 formed of a sheet of cut-glass or oiled
 tissue-paper4  ,when making use of the 
method just described1 it is very       
necessary that the telescope-tube should
 be well balanced4 ,a method by which   
this may be conveniently accomplished   
has been already described in ,chapter  
,i4  ,but1 undoubtedly1 for the         
possessor of a moderately good telescope
 there is no way of viewing the sun's   
features comparable to that now to be   
described1 which has been systematically
 and successfully applied for a long    
series of years by the ,rev4 ,f4        
,howlett4 ,to use his own words3 ,any   
one possessing a good achromatic of not 
more than three inches' aperture1 who   
has a little dexterity with his pencil1 

and a little time at his disposal 7all  
the better if it be at a somewhat early 
hour of the morning7 may by this method 
deliberately and satisfactorily view1   
measure1 and 7if skill suffice7         
delineate most of those interesting and 
grand solar phenomena of which he may   
have read1 or which he may have seen    
depicted1 in various works on physical  
astronomy4#ae  ,the method in question  
depends on the same property which is   
involved in the use of the pyramidal box
 just described1 supplemented 7where    
exact and systematic observation is     
required7 by the fact that objects lying
 on or between the lenses of the        
eye-piece are to be seen faithfully     
projected on the white surface on which 
the sun's image is received4 ,in place1 
however1 of a box carried upon the      
telescope-tube1 a darkened room 7or true
 camera obscura7 contains the receiving 
sheet4  ,a chamber is to be selected1   
having a window looking towards the     
south--a little easterly1 if possible1  

so as to admit of morning observation4  
,all windows are to be completely       
darkened save one1 through which the    
telescope is directed towards the sun4  
,an arrangement is to be adopted for    
preventing all light from entering by   
this window except such light as passes 
down the tube of the telescope4 ,this   
can readily be managed with a little    
ingenuity4 ,mr4 ,howlett describes an   
excellent method4 ,the following1       
perhaps1 will sufficiently serve the    
purposes of the general observer3--,a   
plain frame 7portable7 is to be         
constructed to fit into the window3 to  
the four sides of this frame triangular 
pieces of cloth 7impervious to light7   
are to be attached1 their shape being   
such that when their adjacent edges are 
sewn together and the flaps stretched   
out1 they form a rectangular pyramid of 
which the frame is the base4 ,through   
the vertex of this pyramid 7near which1 
of course1 the cloth flaps are not sewn 
together7 the telescope tube is to be   

passed1 and an elastic cord so placed   
round the ends of the flaps as to       
prevent any light from penetrating      
between them and the telescope4 ,it will
 now be possible1 without disturbing the
 screen 7fixed in the window71 to move  
the telescope so as to follow the sun   
during the time of observation4 ,and the
 same arrangement will serve for all    
seasons1 if so managed that the elastic 
cord is not far from the middle of the  
telescope-tube2 for in this case the    
range of motion is small compared to the
 range of the tube's extremity4  ,a     
large screen of good drawing-paper      
should next be prepared4 ,this should be
 stretched on a light frame of wood1 and
 placed on an easel1 the legs of which  
should be furnished with holes and pegs 
that the screen may be set at any       
required height1 and be brought square  
to the tube's axis4 ,a large ,t-square  
of light wood will be useful to enable  
the observer to judge whether the screen
 is properly situated in the last       

respect4  ,we wish now to direct the    
tube towards the sun1 and this without  
dazzling the eyes as by the ordinary    
method4 ,this may be done in two ways4  
,we may either1 before commencing       
work--that is1 before fastening our     
elastic cord so as to exclude all       
light--direct the tube so that its      
shadow shall be a perfect circle 7when  
of course it is truly directed71 then   
fasten the cord and afterwards we can   
easily keep the sun in the field by     
slightly shifting the tube as occasion  
requires4 ,or 7if the elastic cord has  
already been fastened7 we may remove the
 eye-tube and shift the telescope-tube  
about--the direction in which the sun   
lies being roughly known--until we see  
the spot of light received down the     
telescope's axis grow brighter and      
brighter and finally become a spot of   
sun-light4 ,if a card be held near the  
focus of the telescope there will be    
seen in fact an image of the sun4 ,the  
telescope being now properly directed1  

the eye-tube may be slipped in again1   
and the sun may be kept in the field as 
before4  ,there will now be seen upon   
the screen a picture of the sun very    
brilliant and pleasing1 but perhaps a   
little out of focus4 ,the focusing      
should therefore next be attended to1   
the increase of clearness in the image  
being the test of approach to the true  
focus4 ,and again1 it will be well to   
try the effect of slight changes of     
distance between the screen and the     
telescope's eye-piece4 ,mr4 ,howlett    
considers one yard as a convenient      
distance for producing an excellent     
effect with almost any eye-piece that   
the state of the atmosphere will admit  
of4 ,of course1 the image becomes more  
sharply defined if we bring the screen  
nearer to the telescope1 while all the  
details are enlarged when we move the   
screen away4 ,the enlargement has no    
limits save those depending on the      
amount of light in the image4 ,but1 of  
course1 the observer must not expect    

enlargement to bring with it a view of  
new details1 after a certain magnitude  
of image has been attained4 ,still there
 is something instructive1 ,i think1 in 
occasionally getting a very magnified   
view of some remarkable spot4 ,i have   
often looked with enhanced feelings of  
awe and wonder on the gigantic image of 
a solar spot thrown by means of the     
diagonal eye-piece upon the ceiling of  
the observing-room4 ,blurred and        
indistinct through over-magnifying1 yet 
with a new meaning to me1 there the vast
 abysm lies pictured2 vague imaginings  
of the vast and incomprehensible        
agencies at work in the great centre of 
our system crowd unbidden into my mind2 
and ,i seem to feel--not merely think   
about--the stupendous grandeur of that  
life-emitting orb4  ,to return1 however1
 to observation3--,by slightly shifting 
the tube1 different parts of the solar  
disc can be brought successively upon   
the screen and scrutinized as readily as
 if they were drawn upon a chart4 ,with 

a power of--say about #fj or #hj        
linear--the most minute solar spot1     
properly so called1 that is capable of  
formation 7,mr4 ,howlett believes they  
are never less than three seconds in    
length or breadth7 will be more readily 
detected than by any other method1 see  
,plate #g2 as also will any facul1      
mottling1 or in short1 any other        
phenomena that may then be existing on  
the disc4 ,drifting clouds frequently   
sweep by1 to vary the scene1 and        
occasionally an arial hail- or          
snow-storm4 ,mr4 ,howlett has more than 
once seen a distant flight of rooks pass
 slowly across the disc with wonderful  
distinctness1 when the sun has been at a
 low altitude1 and likewise1 much more  
frequently1 the rapid dash of starlings1
 which1 very much closer at hand1       
frequent his church-tower4  ,an eclipse 
of the sun1 or a transit of an inferior 
planet1 is also much better seen in this
 way than by any other method of        
observing the solar disc4 ,in ,plate #g 

are presented several solar spots as    
they have appeared to ,mr4 ,howlett1    
with an instrument of moderate power4   
,the grotesque forms of some of these   
are remarkable2 and the variations the  
spots undergo from day to day are       
particularly interesting to the         
thoughtful observer4  ,a method of      
measuring the spots may now be          
described4 ,it is not likely indeed that
 the ordinary observer will care to     
enter upon any systematic series of     
measurements4 ,but even in his case1 the
 means of forming a general comparison  
between the spots he sees at different  
times cannot fail to be valuable4 ,also 
the knowledge--which a simple method of 
measurement supplies--of the actual     
dimensions of a spot in miles 7roughly7 
is calculated to enhance our estimate of
 the importance of these features of the
 solar disc4 ,i give ,mr4 ,howlett's    
method in his own words3--  ,cause your 
optician to rule for you on a circular  
piece of glass a number of fine         

graduations1 the #bjjth part of an inch 
apart1 each fifth and tenth line being  
of a different length in order to assist
 the eye in their enumeration4 ,insert  
this between the anterior and posterior 
lenses of a ,huygenian eye-piece of     
moderate power1 say #hj linear4 ,direct 
your telescope upon the sun1 and having 
so arranged it that the whole disc of   
the sun may be projected on the screen1 
count carefully the number of           
graduations that are seen to exactly    
occupy the solar diameter4444 ,it       
matters not in which direction you      
measure your diameter1 provided only the
 sun has risen some #ah or #bj above the
 horizon1 and so escaped the distortion 
occasioned by refraction4#af  ,next let 
us suppose that our observer has been   
observing the sun on any day of the     
year1 say1 if you choose1 at the time of
 its mean apparent diameter1 namely     
about the first of ,april or first of   
,october1 and has ascertained that 7as  
is the case with ,mr4 ,howlett's        

instrument7 sixty-four graduations      
occupy the diameter of the projected    
image4 ,now the semi-diameter of the    
sun1 at the epochs above mentioned1     
according to the tables given for every 
day of the year in the ',nautical       
,almanac' 7the same as in ,dietrichsen  
and ,hannay's very useful compilation7  
is #af' #b1 and consequently his mean   
total diameter is #cb' #d or #aibd4 ,if 
now we divide #aibd by #fd this will1 of
 course1 award as nearly as possible #cj
 as the value in celestial arc of each  
graduation1 either as seen on the       
screen1 or as applied directly to the   
sun or any heavenly body large enough to
 be measured by it4  ,since the sun's   
diameter is about #hej1jjj miles1 each  
graduation 7in the case above specified7
 corresponds to one-#fdth part of       
#hej1jjj miles--that is1 to a length of 
#ac1bef miles on the sun's surface4 ,any
 other case can be treated in precisely 
the same manner4  ,it will be found easy
 so to place the screen that the        

distance between successive graduations 
7as seen projected upon the screen7 may 
correspond to any desired unit of linear
 measurement--say an inch4 ,then if the 
observer use transparent tracing-paper  
ruled with faint lines forming squares  
half-an-inch in size1 he can comfortably
 copy directly from the screen any solar
 phenomena he may be struck with4 ,a    
variety of methods of drawing will      
suggest themselves4 ,mr4 ,howlett1 in   
the paper ,i have quoted from above1    
describes a very satisfactory method1   
which those who are anxious to devote   
themselves seriously to solar           
observation will do well to study4  ,it 
is necessary that the observer should be
 able to determine approximately where  
the sun's equator is situated at the    
time of any observation1 in order that  
he may assign to any spot or set of     
spots its true position in relation to  
solar longitude and latitude4 ,mr4      
,howlett shows how this may be done by  
three observations of the sun made at   

any fixed hour on successive days4      
,perhaps the following method will serve
 the purpose of the general observer    
sufficiently well3--  ,the hour at which
 the sun crosses the meridian must be   
taken for the special observation now to
 be described4 ,this hour can always be 
learnt from ',dietrichsen's ,almanac'2  
but noon1 civil time1 is near enough for
 practical purposes4 ,now it is         
necessary first to know the position of 
the ecliptic with reference to the      
celestial equator4 ,of course1 at noon a
 horizontal line across the sun's disc  
is parallel to the equator1 but the     
position of that diameter of the sun    
which coincides with the ecliptic is not
 constant3 at the summer and winter     
solstices this diameter coincides with  
the other1 or is horizontal at noon2 at 
the spring equinox the sun 7which       
travels on the ecliptic7 is passing     
towards the north of the equator1       
crossing that curve at an angle of      
#bc-a_/b1 so that the ecliptic coincides

 with that diameter of the sun which    
cuts the horizontal one at an angle of  
#bc-a_/b and has its left end above the 
horizontal diameter2 and at the autumn  
equinox the sun is descending and the   
same description applies1 only that the 
diameter 7inclined #bc-a_/b to the      
horizon7 which has its right end        
uppermost1 now represents the ecliptic4 
,for intermediate dates1 use the        
following little table3--               
----------------------------------------
----------------------------------      
,date4              ,dec4 #bb;,jan4     
#e;,jan4 #bj;,feb4 #d;,feb4 #ai,mar4 #e 
,mar4 #ba 7,circiter47                  
,june #f,may #ba ,may #e ,apr4 #bj;,apr4
 #e                                     
----------------------------------------
--------------------------- ,inclination
 of     ,left   ,left  ,left   ,left    
,left   ,left   ,left ,ecliptical       
,diameter                               
of ,sun to the      #j #j'  #fbd' #abad'
 #agc' #bjcf' #bbdd' #bcbg' ,horizon4#ag

       ,right  ,right ,right  ,right    
,right  ,right  ,right                  
----------------------------------------
--------------------------- ,date4      
,dec4 #g,nov4 #bb,nov4 #g,oct4 #bc,oct4 
#h  7,circiter47        ,jan4 #ba;,july 
#g;,july #bc;,aug4 #f;,aug4 #bc,sept4   
#g,sept4 #bc                            
----------------------------------------
----------------------------------  ,now
 if our observer describe a circle1 and 
draw a diameter inclined according to   
above table1 this diameter would        
represent the sun's equator if the axis 
of the sun were square to the           
ecliptic-plane4 ,but this axis is       
slightly inclined1 the effect of which  
is1 that on or about ,june #aj the sun  
is situated as shown in fig4 #ad with   
respect to the ecliptic ab2 on or about 
,september #aa he is situated as shown  
in fig4 #ac2 on or about ,december #aa  
as shown in fig4 #ab2 and on or about   
,march #aj as shown in fig4 #ae4 ,the   
inclination of his equator to the       

ecliptic being so small1 the student can
 find little difficulty in determining  
with sufficient approximation the       
relation of the sun's polar axis to the 
ecliptic on intermediate days1 since the
 equator is never more inclined than in 
figs4 #ab and #ad1 never more opened out
 than in figs4 #ac and #ae4 ,having then
 drawn a line to represent the sun's    
ecliptical diameter inclined to the     
horizontal diameter as above described1 
and having 7with this line to correspond
 to ab in figs4 #ab-ae7 drawn in the    
sun's equator suitably inclined and     
opened out1 he has the sun's actual     
presentation 7at noon7 as seen with an  
erecting eye-piece4 ,holding his picture
 upside down1 he has the sun's          
presentation as seen with an            
astronomical eye-piece--and1 finally1   
looking at his picture from behind      
7without inverting it71 he has the      
presentation seen when the sun is       
projected on the screen4 ,hence1 if he  
make a copy of this last view of his    

diagram upon the centre of his screen1  
and using a low power1 bring the whole  
of the sun's image to coincide with the 
circle thus drawn 7to a suitable scale7 
on the screen1 he will at once see what 
is the true position of the different   
sun-spots4 ,after a little practice the 
construction of a suitably sized and    
marked circle on the screen will not    
occupy more than a minute or two4       
,illustration3 ,fig4 #ab4               
,illustration3 ,fig4 #ac4               
,illustration3 ,fig4 #ad4               
,illustration3 ,fig4 #ae4  ,it must be  
noticed that the sun's apparent diameter
 is not always the same4 ,he is nearer  
to us in winter than in summer1 and1 of 
course1 his apparent diameter is greater
 at the former than at the latter       
season4 ,the variation of the apparent  
diameter corresponds 7inversely7 to the 
variation of distance4 ,as the sun's    
greatest distance from the earth is     
#ic1jjj1jjj miles 7pretty nearly7 and   
his least #ij1jjj1jjj1 his greatest1    

mean1 and least apparent diameters are  
as #ic1 #ia-a_/b1 and #ij respectively2 
that is1 as #fb1 #fa1 and #fj           
respectively4  ,mr4 ,howlett considers  
that with a good #c-;inch telescope1    
applied in the manner we have described1
 all the solar features may be seen1    
except the separate granules disclosed  
by first-class instruments in the hands 
of such observers as ,dawes1 ,huggins1  
or ,secchi4 ,facul may1 of course1 be   
well seen4 ,they are to be looked for   
near spots which lie close to the sun's 
limb4  ,when the sun's general surface  
is carefully scrutinised1 it is found to
 present a mottled appearance4 ,this is 
a somewhat delicate feature4 ,it        
results1 undoubtedly1 from the combined 
effect of the granules separately seen  
in powerful instruments4 ,sir ,john     
,herschel has stated that he cannot     
recognise the marbled appearance of the 
sun with an achromatic4 ,mr4 ,webb1     
however1 has seen this appearance with  
such a telescope1 of moderate power1    

used with direct vision2 and certainly  
,i can corroborate ,mr4 ,howlett in the 
statement that this appearance may be   
most distinctly seen when the image of  
the sun is received within a            
well-darkened room4  ,my space will not 
permit me to enter here upon the        
discussion of any of those interesting  
speculations which have been broached   
concerning solar phenomena4 ,we may hope
 that the great eclipse of ,august1     
#ahfh1 which promises to be the most    
favourable 7for effective observation7  
that has ever taken place1 will afford  
astronomers the opportunity of resolving
 some important questions4 ,it seems as 
if we were on the verge of great        
discoveries1--and certainly1 if         
persevering and well-directed labour    
would seem in any case to render such   
discoveries due as man's just reward1 we
 may well say that he deserves shortly  
to reap a harvest of exact knowledge    
respecting solar phenomena4     ,,the   
,,end4    ,,footnotes3  ,footnote #a3   

,such a telescope is most powerful with 
the shortest sight4 ,it may be remarked 
that the use of a telescope often       
reveals a difference in the sight of the
 two eyes4 ,in my own case1 for         
instance1 ,i have found that the left   
eye is very short-sighted1 the sight of 
the right eye being of about the average
 range4 ,accordingly with my left eye a 
#e-a_/b-;foot object-glass1 alone1 forms
 an effective telescope1 with which ,i  
can see ,jupiter's moons quite          
distinctly1 and under favourable        
circumstances even ,saturn's rings4 ,i  
find that the full moon is too bright to
 be observed in this way without pain1  
except at low altitudes4  ,footnote #b3 
,betelgeuse--commonly interpreted the   
,giant's ,shoulder--ibt-al-jauza4 ,the  
words1 however1 really signify1 the     
armpit of the central one1 ,orion being 
so named because he is divided centrally
 by the equator4  ,footnote #c3 ,i have 
never been able to see more than four   
with a #c-c_/d-;inch aperture4 ,i give a

 view of the trapezium as seen with an  
#h-;inch equatorial4  ,footnote #d3 ,sir
 ,w4 ,herschel several times saw epsilon
 ,lyr as a double4 ,bessel also relates 
that when he was a lad of thirteen he   
could see this star double4 ,i think    
persons having average eye-sight could  
see it double if they selected a        
suitable hour for observation4 ,my own  
eye-sight is not good enough for this1  
but ,i can distinctly see this star     
wedged whenever the line joining the    
components is inclined about #de to the 
horizon1 and also when ,lyra is near the
 zenith4  ,footnote #e3 ,they were so   
described by ,admiral ,smyth in #ahci4  
,mr4 ,main1 in #ahfb1 describes them as 
straw-coloured and reddish1 while ,mr4  
,webb1 in #ahfe1 saw them pale-yellow   
and lilac6  ,footnote #f3 ,or the       
observer may sweep from omicron towards 
nu1 looking for ,r about two-fifths of  
the way from omicron to nu4  ,footnote  
#g3 ,here a single period only is taken1
 to get back to a convenient hour of the

 evening4  ,footnote #h3 ,here a single 
period only is taken1 to get back to a  
convenient hour of the evening4         
,footnote #i3 ,i have constructed a     
zodiac-chart1 which will enable the     
student to mark in the path of a planet1
 at any season of the year1 from the    
recorded places in the almanacs4        
,footnote #aj3 ,it is convenient to     
remember that through precession a star 
near the ecliptic shifts as respects the
 ,r4,a4 and ,dec4 lines1 through an arc 
of one degree--or nearly twice the      
moon's diameter--in about #gb years1 all
 other stars through a less arc4        
,footnote #aa3 ,mercury is best seen    
when in quadrature to the sun1 but not  
7as ,i have seen stated7 at those       
quadratures in which he attains his     
maximum elongation from the sun4 ,this  
will appear singular1 because the       
maximum elongation is about #bg1 the    
minimum only about #ah4 ,but it happens 
that in our northern latitudes ,mercury 
is always south of the sun when he      

attains his maximum elongation1 and this
 fact exercises a more important effect 
than the mere amount of elongation4     
,footnote #ab3 ,it does not seem to me  
that the difficulty of detecting        
,mercury is due to the difficulty of    
identifying it amongst the surrounding  
stars1 during the short time that it can
 be seen 7,hind's ',introduction to     
,astronomy'74 ,there are few stars which
 are comparable with ,mercury in        
brilliancy1 when seen under the same    
light4  ,footnote #ac3 ,i may notice    
another error sometimes made4 ,it is    
said that the shadow of a satellite     
appears elliptical when near the edge of
 the disc4 ,the shadow is in reality    
elliptical when thus situated1 but      
appears circular4 ,a moment's           
consideration will show that this should
 be so4 ,the part of the disc concealed 
by a satellite near the limb is also    
elliptical1 but of course appears round4
  ,footnote #ad3 ,from a paper by ,mr4  
,breen1 in the ',popular ,science       

,review1' ,october1 #ahfd4  ,footnote   
#ae3 ',intellectual ,observer' for      
,july1 #ahfg1 to which magazine the     
reader is referred for full details of  
,mr4 ,howlett's method of observation1  
and for illustrations of the appliances 
he made use of1 and of some of his      
results4  ,footnote #af3 ,as the sun    
does not attain such an altitude as #ah 
during two months in the year1 it is    
well to notice that the true length of  
the sun's apparent solar diameter is    
determinable even immediately after     
sun-rise1 if the line of graduation is  
made to coincide with the horizontal    
diameter of the picture on the          
screen--for refraction does not affect  
the length of this diameter4  ,footnote 
#ag3 ,the words ,left and ,right        
indicate which end of the sun's         
ecliptical diameter is uppermost at the 
dates in upper or lower row             
respectively4     ,,london3  ,,printed  
,,by ,w4 ,,clowes ,,and ,,sons1 ,,duke  
,,street1 ,,stamford ,,street1 ,,and    

,,charing ,,cross4