,,william ,,gilbert1 ,,and ,,terrestrial
      ,,magnetism ,,in ,,the ,,time ,,of
      ,,queen ,,elizabeth3 ,a           
,,discourse      ,,by ,,silvanus ,p4    
,,thompson1 ,f4,r4,s4                   
,,william ,,gilbert ,,and ,,terrestrial 
,,magnetism ,,in ,,the ,,time ,,of      
,,queen      ,,elizabeth4      ,william 
,gilbert1 the father of electrical      
science1 was born in  ,colchester in    
#aedj4 ,educated at ,st4 ,john's        
,college1 ,cambridge1 where  he took his
 degree as ,doctor of ,medicine in      
#aefi1 he settled1 after  four years of 
foreign travel1 in ,london in #aegc1 and
 was admitted to  the ,royal ,college of
 ,physicians1 of which he became        
,censor1 ,treasurer1  and1 in #aeii1    
,president4 ,he was in ,february1 #afja1
 appointed personal  ,physician to the  
,queen1 whom he attended in her last    
illness4 ,he came  of a well-known ,east
 ,anglian family1 and held extensive    
landed estates  in ,essex and ,suffolk4 
,he survived the ,queen only eight      

months1 dying  ,november #cjth1 #afjc4  
,gilbert's monumental work1 the ,de     
,magnete1 published in #afjj1 marks  an 
era in magnetic science4 ,for some four 
hundred years the employment  of the    
magnetic needle in navigation had been  
known both in ,northern  and ,southern  
,europe4 ,while it is possible that the 
primitive use of  the loadstone may be  
ascribed to the ,baltic1 it is certain  
that the  employment of a pivotted      
needle1 and the addition of a rose of   
the  winds as a compass card both       
originated in the ,mediterranean4 ,the  
pivotted needle is described in the     
,epistle of ,peter ,peregrinus1  written
 in #abfi2 while the earliest known     
compass-card marked with  the initials  
of the names of the winds is that       
ascribed to ,jachobus  ,giraldis1 of    
#adbf1 in the ,biblioteca ,marciana in  
,venice4 ,the manner of  use in         
,elizabethan times of the loadstone and 
of the compass may be  gathered from    
,olaus ,magnus 7,historia de ,gentibus  

,septentrionalibus1  #aeee71 from ,pedro
 de ,medina 7,arte de ,nauegar1 #aede71 
,martinus ,cortes  7,breve compendio de 
la sphera1 #aeef71 ,blundevile          
7,exercises1 #aeid71  ,norman 7,newe    
,attractive1 #aeha71 ,borough 7,a       
discours of the ,variation  of the      
,cumpas1 #aeha71 ,pedro ,nuez           
7,instrumenta ,artis ,navigandi1        
#aeib71 ,barlow 7,the ,navigators       
,supply1 #aeig71 ,nautonier 7,mcometrie 
de l',eyman1 #afjb71 and ,stevin 7,die  
,havenvinding1 #aeii74    ,at the time  
when steering by the compass was        
introduced into  navigation1 the compass
 pointed in ,middle ,europe so nearly   
truly to the  north that with the rough 
instrumental appliances at hand its     
deviation  from the true north was      
seldom noticed1 or if noticed ascribed  
to some  error in the setting of the    
needle4 ,later the compass-makers began 
to set their needles slightly askew     
beneath the card1 according to  the     
variation in the place of origin4       

,norman 7#aeha7 states that those  used 
in the ,levant1 made in ,sicily1 ,genoa1
 or ,venice1 had the needles  straight1 
while those used in ,denmark and        
,flanders had them set at               
three-quarters of a point1 or a whole   
point1 to the eastward2 while  those    
made in ,spain1 ,portugal1 ,france1 and 
,england1 had the needles set  half a   
point to the east4 ,those for ,russia   
were set at three seconds  of a point4  
,gilbert denounced these devices as     
tending to obscure  the true facts4     
,gradually it became recognized1        
probably after the  voyage of ,columbus1
 when the manifest change in the        
declination of the  needle nearly caused
 mutiny of the sailors1 that the        
direction of the  needle differs at     
different places2 and accordingly       
navigators began to  collect data4 ,the 
record of the voyage of ,columbus states
 that during  his second voyage in #adif
 he used for steering the observations  
made  on the declination during his     

first voyage4 ,the secret of ,sebastian 
,cabot1 which he declared when dying to 
be a divine revelation to  him1 can have
 been little else than the idea of using
 in navigation  the local declinations  
of the compass4 ,on the other hand1     
,pedro de  ,medina flatly denied the    
existence of the declination1 adding    
that  if the compass did not show the   
pole1 the fault lay in the defective    
construction of the compass itself4     
,columbus had found a point #b-a_/b     
east of ,corvo1 in the ,azores1 where   
there was no variation1 and other       
navigators explored the agonic lines    
which crossed the ,atlantic and  the    
,indian ocean4 ,according to ,humboldt1 
,alonzo de ,santa ,cruz in #aecj        
constructed the first general variation 
chart4 ,but along with this  development
 of practical interest in the subject   
there grew up a crop  of wild legends to
 account for the irregularities         
observed4 ,the reason  why the compass  
needle pointed north1 and the reason why

 it did not  point truly north1 were    
alike proclaimed to be due to the stars1
 to  the influence of spirits1 or to the
 existence of loadstone mountains  of   
uncertain locality and of fabulous      
power4 ,the old traditions of the       
,arabian ,nights1 dressed in a newer    
setting1 found themselves justified  by 
the insertion in maps of loadstone      
rocks1 the position of which  changed at
 the fancy of the chartographer4        
,ptolemy had located them in  the       
,manioles2 ,olaus ,magnus declared them 
to be under the pole2 ,garzias  ab      
,horto situated them in the region of   
,calcutta4 ,the map of ,johann  ,ruysch1
 which adorned the edition of ,ptolemy1 
publisht at ,rome in #aejh1  showed four
 magnetic islands in the ,arctic        
,circle4 ,martinus ,cortes  placed the  
loadstone mountains in ,sarmatia4       
,mercator in his great chart  depicted  
two great rocks rising from the sea to  
the north of eastern  ,siberia1 one     
being drawn on the supposition that at  

,st4 ,michael the  compass points due   
north1 while the other is further north 
on the  supposition that the compass    
points due north at ,corvo4 ,the map of 
,cornelius ,wytfliet1 #aeig1 shows the  
same phantom islands4 ,blundevile1      
writing in #aeid of the now lost map of 
,peter ,plancius1 mentions that  he sets
 down the pole of the loadstone somewhat
 to southward of the  islands that lie  
east of ,groynelande4    ,meantime      
another significant fact had been       
discovered in #aegf by  ,robert ,norman1
 of ,limehouse1 compass-maker1 namely1  
the tendency of  the magnetized needle  
to dip its northern end downwards4      
,noticing this  as a circumstance that  
occasioned him some trouble in the      
construction  of his compasses1 he      
thereupon devised a dipping-needle1 and 
measured  the dip1 which for this ,cyty 
of ,london ,i finde by exact            
obseruations  to be about #ga degrees   
#ej mynutes4 ,he attributed both the    
declination  and the dip of the needle  

to the existence of a poynt respective1 
which the needle respected or indicated1
 but toward which it was not  attracted4
 ,the first authoritative treatise on   
the variation of the  compass was the   
tract by ,william ,borough1 comptroller 
to the ,navy1  who in #aehj found an    
eastward declination of #aa #ae' at     
,limehouse4  ,borough had himself       
travelled in northern regions and had   
found at  ,vaigats a westerly           
declination of #g degrees1 whereas by   
,norman's  theory of the respective     
point there should have been an easterly
  declination of #di #bb'4 ,the great   
navigators were continually bringing    
home fresh information4 ,drake1         
,lynschoten1 ,cavendish1 ,hariot all    
contributed2 as did lesser men such as  
,abraham ,kendall1 sailing-master  to   
,sir ,robert ,dudley 7the soi-disant    
,duke of ,northumberland71 and          
afterward companion of ,drake in his    
last voyage4 ,teachers of navigation    
such as ,simon ,stevin of ,bruges and   

,edward ,wright1 lecturer to the  ,east 
,india ,company1 might record and       
tabulate3 but a master-mind was  wanting
 to forge some larger and consistent    
doctrine which should  afford a grasp of
 the whole subject4 ,such an one arose  
in ,dr4 ,william  ,gilbert4 ,nurtured1  
as we have seen1 in the ,cambridge which
 had so  recently been the home of      
,linacre and of ,kaye--the ,kaye who    
founded  ,caius ,college--,gilbert had1 
during his subsequent sojourn in ,italy1
  conversed with all the learned men of 
his time4 ,he had experimented  on the  
magnet with ,fra ,paolo ,sarpi3 he had1 
there is reason to think1  met ,giordano
 ,bruno3 he was the friend and          
correspondent of ,giovanni  ,francesco  
,sagredo4 ,being a man of means and a   
bachelor1 he spent money  freely upon   
books1 maps1 instruments1 minerals1 and 
magnets4 ,for twenty  years he          
experimented ceaselessly1 and read1 and 
wrote and speculated1  and tested his   
speculations by new experiments4 ,for   

eighteen years he  kept beside him the  
manuscript of his treatise1 which in the
 year  #afjj saw the light under the    
title of ,de ,magnete1 to which was     
added  the sub-title3 magneticisque     
corporibus1 et de magno magnete tellure1
  physiologia nova4 ,that which ,gilbert
 had in fact perceived1 and which  none 
before him had glimpsed even dimly1 was 
that the globe of the  earth itself     
acted as a great loadstone1 and that the
 tendency of  the needle to point in a  
polar direction was due to the globe    
acting  as a whole4 ,so he boldly put   
into his title-page the statement that  
his new philosophy was concerning the   
great magnet the earth3 and  in chapter 
after chapter he set himself to describe
 the experiments  upon which he founded 
his famous induction4 ,the phrase       
terrestrial  magnetism does not occur in
 any of the prior treatises1 because    
the idea had not presented itself4      
,gilbert piled proof upon proof1        
sometimes most cogently1 as when he     

constructed loadstone globes1 or        
terrellas to serve as magnetic models of
 the earth2 sometimes with  indifferent 
logic1 as when he pointed to the iron   
ore in the earth  and reasoned that the 
magnet tended to conform to 7i4e4 turn  
itself  toward7 the homogenic substance 
of the body from which it had been dug4 
,the local deviations of the compass he 
sought to account for by the            
irregularities of the earth's crust1 and
 maintained that the compass  tended    
always1 at places off the coast of a    
continent1 to be deflected  somewhat    
toward that continent4 ,his syllogism   
was based on the fact  that at that date
 all the way up the ,atlantic seaboard  
of ,europe1 from  ,morocco to ,norway1  
the variation was eastward4 ,he argued  
that this was  a universal law4 ,but    
even within one generation1 as may be   
seen in  ,purchas his ,pilgrims1 in the 
narrative of the voyage of ,bylot and   
,baffin1 the generality of the law was  
questioned4 ,gilbert reasoned on  such  

knowledge as he had1 and this did not   
include any notion of the  secular      
changes in the declination4 ,in his     
time1 as he tells us1 the  variation of 
the compass at ,london was #aa-a_/c     
degrees4 ,what he did not  know was that
 this was a diminishing quantity which  
in fifty-seven  years would be reduced  
to zero1 to be succeeded by a westward  
declination that would last for nearly  
three hundred years4 ,for the  facts as 
known in the thirty years succeeding    
,gilbert's death1 see the  remarkable   
and scarce volume of ,gellibrand3 ,a    
,discourse ,mathematical  on the        
,variation of the ,magneticall ,needle  
7#afce74    ,gilbert's treatise is a    
skilful literary achievement in which   
there is  no trace to reveal whether any
 part was written before the rest4 ,it  
is  divided systematically into six     
books4 ,the sixth book only appears to  
suffer from some incompleteness4 ,it    
relates not so much to the magnet  as to
 the ,copernican theory of the universe1

 which doctrine ,gilbert had  eagerly   
espoused1 and which he was the first in 
,england to proclaim4  ,it is known from
 a letter to ,barlow1 printed in #afaf1 
that he intended  to add to it certain  
chapters descriptive of some of his     
instruments1  but he had not completed  
these before his death4 ,the first book 
treats  of historic accounts of the     
loadstone1 of its origin and properties1
  of iron ores in general1 and of the   
fables and vain opinions which in  the  
handling of ,paracelsus and of the      
schoolmen had grown up around the       
magnet4 ,the second book is on the      
magnetic motions1 and primarily on  the 
attractions and repulsions between      
loadstones1 between loadstone  and iron1
 and between magnetic needles4 ,in this 
book occurs the notable  digression upon
 the subject of amber and the electric  
forces of amber  and of other substances
 which when rubbed show1 as he          
discovered1  similar electrical powers4 
,an analysis of this part1 and a summary

 of  ,gilbert's electrical discoveries  
will be found in the ,notes printed for 
the ,gilbert ,club to accompany the     
,english translation 7#aijj7 of the  ,de
 ,magnete4 ,after this digression       
,gilbert returns to the attractive      
properties of the loadstone1 and to the 
way they are affected by giving  it     
different shapes4 ,in the course of this
 enquiry1 he announces  his discovery of
 the augmentation of the power of the   
loadstone by  arming it with iron caps1 
an invention which caused ,galileo to   
say3 ,i  extremely praise1 admire1 and  
envy this author for that a conception  
so  stupendous should come into his     
mind4 ,i think him moreover worthy of   
extraordinary applause for the many new 
and true observations that he  has made4
 ,gilbert further pointed out that the  
loadstone is surrounded  by a sort of   
atmosphere or orbe of virtue within     
which the magnetical  effects can be    
observed4 ,book #c1 on the directive    
force of the magnet1  is full of most   

instructive experiments1 in which the   
terrella figures  largely1 relating to  
the question how one magnet influences  
another  and tends to make it point     
toward it4 ,all this was leading up to  
the  theory of terrestrial magnetism2   
for we find him naming the parts of  his
 loadstone globes with poles1 equator   
and meridians4 ,in this book  he dilates
 on the observation that vertical iron  
rods1 such as the  finial on the ,church
 of ,st4 ,john at ,rimini1 spontaneously
 acquired  magnetic properties4 ,this he
 traced to the influence of the earth1  
and  demonstrated the effect by         
magnetizing iron bars by simply         
hammering  them on the anvil while they 
lay in a north and south position4 ,book
 #d  deals with the ,declination1 or1 as
 it was then called1 the variation  of  
the compass4 ,he discusses its          
observation and measurement1 the        
influence of islands1 the results       
obtained by travellers to distant       
parts1 ,nova ,zembla1 the ,guinea coast1

 the ,canary ,isles1 ,florida1          
,virginia1 ,cape ,race1 and ,brazil4    
,then he recounts his experiments with  
terrellas having uneven surfaces to     
represent the irregularities of  the    
earth's crust4 ,he points out errors    
arising from the fallacious  practice of
 setting the needle obliquely under the 
card4 ,he considers  in separate        
chapters the variations in ,nova        
,zembla1 in the ,pacific1  in the       
,mediterranean1 and in the ,eastern     
,ocean4 ,the fifth book is on  the ,dip4
 ,gilbert seized with avidity on        
,norman's discovery of this  effect1 and
 devised an improved form of            
dipping-needle4 ,he experimented  on the
 dip of compass-needles placed at       
different points over his  terrella1 and
 evolved a theory on the proportion     
which he conceived to  exist between the
 latitude and the dip4 ,arguing from all
 too imperfect  data1 he propounded the 
view that the dip was the same in any   
given  latitude2 and proposed that      

seamen should ascertain their latitudes 
by simply observing the dip4 ,he was    
aware that local irregularities  might  
occur1 as they do in the declination2   
but was not deterred by  this knowledge 
from propounding his theory with much   
circumstance  and considerable          
geometrical skill4 ,after the           
publication of his  book he developed   
the theory still further and gave it to 
,blundevile  for publication4 ,at       
,gilbert's suggestion ,briggs of        
,gresham ,college  calculated out a     
table of dip and latitude4 ,it was1     
however1 soon found  that the facts     
deviated more or less widely from the   
theory4 ,further  observations in other 
lands showed the method to be           
impracticable2 and  ,gilbert's hope to  
give to the mariner a magnetic measure  
of latitude  remained unfulfilled4 ,book
 #e closes with an eloquent passage in  
which  ,gilbert affirmed the            
neo-,platonic doctrine of the animate   
nature of  the universe1 and asserted   

that ,thales was right when he held 7as 
,aristotle relates in the ,de ,anima7   
that the loadstone was animate1  being  
part of and indeed the choice offspring 
of its animate mother the  earth4 ,book 
#f1 as already mentioned1 is devoted to 
,copernican ideas1  and contains        
,gilbert's one contribution to the      
science of ,astronomy1 in  his remark   
that the fixed stars 7previously        
regarded as fixed in the  eighth of the 
celestial spheres at one common distance
 from the central  earth7 were in       
reality set in the heavens at various   
distances from the  earth4    ,from this
 brief analysis it will be seen that    
,gilbert's claims to  eminence rest not 
upon any particular discovery or        
invention1 but upon  his having built up
 a whole experimental magnetic          
philosophy on a truly  scientific basis1
 in place of the vague and wild         
speculations which  had previously been 
accepted4 ,by his magnificent           
generalization from  the small scale    

models to the globe itself1 supported   
from point to  point by experimental    
researches1 he created the science of   
terrestrial  magnetism4 ,if from the    
imperfection of the data at his disposal
 he  fell into sundry errors of detail1 
he yet founded the method of            
philosophizing by which those errors    
were in due time corrected4 ,and if  for
 nothing else than his masterly         
vindication of scientific method1  and  
his rescue of the subject of magnetism  
from the pedantry and  charlatanry into 
which in the preceding ages it had      
lapsed1 his memory  must be held in high
 honour4    ,alas that of the           
personality of so great a man so little 
should be  known4 ,a brief but          
characteristic biography of him is      
enshrined by old  ,fuller in his        
,worthies4 ,the poet ,dryden1 and the   
epigrammatist ,owen1  celebrated him in 
still briefer verse4 ,his portrait1     
which hung for  nigh two hundred years  
in the ,schools ,gallery1 at ,oxford1   

disappeared a  century ago1 leaving only
 a poor engraving to perpetuate his     
scholarly  countenance4 ,doubtless he is
 one of the four physicians depicted  by
 the pencil of ,camden in his famous    
cartoon 7now in the ,british  ,museum71 
as walking in the funeral procession of 
,queen ,elizabeth4 ,of  his handwriting 
not a vestige was known until about five
 years ago1  when a signature was       
unearthed in the ,record ,office4       
,subsequently four  signatures were     
found in the books of ,st4 ,john's      
,college2 and recently  there has come  
to light a volume of ,aristotle bearing 
,gilbert's own  marginal notes4 ,his    
will lies at ,somerset ,house1 but it is
 only a copy4  ,of his fine collection  
of minerals and loadstones1 which with  
his maps1  books1 manuscripts1 and      
correspondence with ,sarpi and ,sagredo 
and  others1 he bequeathed to the       
,college of ,physicians1 nothing        
remains3  they perisht in the ,great    
,fire of ,london4 ,in a quiet corner of 

the ,city  of ,colchester stands the    
quaint old house where he lived1 and    
where1  according to local tradition1 he
 once received the ,queen4 ,and hard by 
it is the church of ,holy ,trinity1 in  
which a mural tablet records his        
virtues and marks his last resting      
place4 ,but his true monument is  the   
immortal treatise in which he laid the  
foundations of terrestrial  magnetism   
and of the experimental science of      
electricity4    ,to the names of the men
 who made great the age of ,queen       
,elizabeth1 who  added lustre to the    
,england over which she ruled1 and made 
it famous  in foreign discovery1 in     
sea-craft1 in literature1 in poetry1 and
 in  drama1 must be joined that of the  
man who equally added lustre in         
science1 ,doctor ,william ,gilbert4     
,this discourse on ,william ,gilbert and
 terrestrial magnetism     in the time  
of ,queen ,elizabeth was delivered by   
,silvanus       ,p4 ,thompson at the    
meeting of the ,royal ,geographical     

,society on ,march twenty-third         
,,mdcccciii on the           occasion of
 the tercentenary of the death of       
,queen ,elizabeth1 and is now printed   
by ,charles ,whittingham                
and ,company at the                     
,chiswick ,press4    ,illustration      
,transcriber's note3 ,the original book 
used the long s1 which has been  changed
 to the modern s here4 ,other archaic   
spellings have not been  changed4       
,the illustrations are small            
decorations4