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t . * 
 
 
 RliY RECORDS 
 
 OF THE 
 
 MAGNETIC DECLINATION 
 
 NORTH A 
 
 By JOHN LANGTON, M.A., Pr]:s.ii»knt. 
 
 I • 
 
 f)e^5 befol'e \\\z Jilei'^i*() ^r|3 ifi^toKcjjl Soeletij, Qijebee. 
 
 QUEBEC: 
 PRIJ^TED BY HUNTER, ROSE & CO., ST. UR3ULE STREET. 
 
 1865. 
 
 Sft' 
 
 \ 
 
SOME EARLY RECORDS OF THE MAGNETIC 
 DECLINATION IN NORTH AMERICA. 
 
 
 Bv JOHN LANGTON, M.A., PnESiDBirr. 
 
 {Jtead he/ore the Sovkty, Mth May, 1865.) 
 
 Mr. Fletcher having annouDced his intention of reading to the 
 Society a paper upon the change in the variation in Canada, as 
 deduced from the records of the Crown Lands Department; I 
 thought it might not be uninteresting to call attention to some 
 very much more ancient observations, which I have met with in the 
 accounts of the earlier explorers of this part of North America. 
 The attention which of late years has been given to all magnetic 
 phenomena, and the care with which observations are made in 
 almost all parts of the globe, bid fair to give us some insight into 
 the causes which influence the change in the magnetism of the 
 earth, and into the laws which regulate it. But as the secular 
 change in the variation is very alow, and even if it is really 
 periodic in its character, it has a cycle embracing some centuries, 
 we must look back to the records of the past to obtain any 
 accurate idea of its progress. With this view, collections have been 
 made of all recorded observations for more than two hundred years, 
 and maps have been published as deduced from them, shewing 
 the isogonal lines as they existed at different dates during the 
 interval. The earlier observations, however, are both few in 
 n|imber, and surrounded with much uncertainty, from the imper- 
 fibtion of the instruments in use, and from the doubt how far 
 they may have been affected by local attraction, the influence of 
 which seems hardly to have been appreciated till a much later 
 period. Observations made on board ship, before the subject of 
 the ship's compass error had been studied, and detached observa- 
 tions where no others have been recorded at nearly the same time 
 
BARLY RECORDS 0¥ THK MAWNETIC 
 
 or in the same neighborhood, mUBt be received with coDsidertble 
 oautioD, and it is only when we hate a series of observations, con- 
 sistent with themselves, that we can place much reliance upon the 
 results. 
 
 In looking over the declinations, as observed by the various 
 land-surveyors in Upper Canada, which were obligingly coinmu- 
 nicated to me by Mr, :?letcher, one could not fail to be struok 
 with the extraordinary differenucs obtained by di£Eerent surveyor^, 
 and often by the same person in the same neighborhood. Much 
 of this is no doubt owing to careless&ess in the observations, and 
 imperfection in the instruments used, but, in a great measure also, 
 it e^dently arises from local attraction. But if for this reason we 
 can place no great faith in an isolated observation, if we take a 
 number of them, nearly about the same period, and in various 
 parts of the satne region, we may obtain a sort of average, which 
 may bo depended upon as nearly correct. The whole surveyed 
 portion of Canada forms such a narrow strip of land, that it hardly 
 affords space enough to determine with any accuracy the direction 
 of any isogonal line ; but the locality in which such a line crosses 
 Canada may be givoo with tolerable precision, and the direction 
 may be obtained by comparing it with the ascertained declination 
 on the coast. Thus, from 1S.19 to 1823, there appear to have been 
 about twenty townships surveyed, in which the needle did not 
 deviate as much as a degree either to the east or west of north ; and 
 the line of no declination, about 1820, passed through the counties 
 of Brant, Waterloo and Wellington. Similarly at the same date the 
 line of 5° westerly variation, passed through the counties of Leeds 
 and Lanark. 
 
 By thus multiplying observations, both in different places, andi 
 at successive dates, we may also conclude that some remarkable 
 discrepancies which present themselves are not mere errors, or the 
 effects of immediate local attraction ; but that some considerable 
 sections of country really differ in their declination from the 
 general course of the lines. Thus it would appear as if the line of 
 no variation about 1820 bifarcated as it approached the shores 
 
UBCLIVAnOlS IN NORTH AMERICA. 5 
 
 of I«ake Erie, and ihut the wholo regioa about Lake Simooe nas 
 had, over a period of many yean, a ieaa w«ateriy deolination than 
 ooe would expect from that which prevails in the oouniry adjoiu- 
 iDg it. 
 
 It is principally for this reason that I think the conclusions of 
 Mr. Fletcher may have considerable value, though many of tho 
 individual observations are doubtless not very trustworthy; and 
 this is also one of the reasons why I attach some importance to the 
 determinations which form the subject of tl^is communication — 
 because they are a series, and consistent with each other. More- 
 over, rude as the method was by which they were made, it could 
 only have been practised on shore, and they are therefore free from 
 the disturbing effects of local attraction, which, without the greatest 
 precautions, are liable to occur on board ship. 
 
 Their early date is also an important feature. In Europe trust- 
 worthy observations are recorded from a somewhat earlier period, 
 though not in any great number ; but in the list given by Han- 
 steen, from which his map for 1600 is compiled, there are none 
 recorded in this part of North America nearly so far back. Tho 
 earliest in the list is that of Bressani for Quebec, which is evidently 
 taken at second hand, for the date is not quite correctly assigned) 
 whilst the declinations as recorded by him on the Great Bank, and 
 in the country of the Hurons, are < r;<itted. 
 
 Indeed, when Champlain explored . he coasts of North America, 
 in the very commencement of the 17th century, the subject was 
 only just commencing to attract attention amongst navigators and 
 men of science. It is often stated that the variation of the com- 
 pass was not known until it was noticed by Columbus, and that 
 , the discovery that the needle no longer pointed to the north, almost 
 i^ave rise to a mutiny amongst his crew. This, however, is a 
 mistake, for the variation is distinctly alluded to by Petrus Perc- 
 grinus, in the latter part of the 13th century, and the amount of 
 it is mentioned, though too vaguely to base any conclusions upon 
 it. It is probable that we do owe to Columbus the first distinct 
 information, that the variation is not the same in all parts of the 
 
6 
 
 EARLY RECORDS OF THE MAGNETIC 
 
 world, and tbut tho needle vhioh pointed east of north on the 
 shores of Europe, had pointed very muoh to the west of north 
 before ho reached those of America. From this time the fact was 
 no doubt familiar to navigators; but I believe that the first known 
 work, in which the importance to keeping a register of the vfiria- 
 tion in diflfcrent parts of the world is enforced, is a treatise on 
 navigation by Prince Maurice of Nassau, published in 1599. 
 Only four years after this Champlaiu was exploring ^he coasts of 
 New England uud Nova Scotia, and that he was deeply impressed 
 with tho Value of such observations is evident from tho instruc- 
 tions ho gives in his Traiti de la Marine, and iu tho explanation 
 of his maps. It had, indeed, in his eyes a greater importance 
 then than it would have had, if he had pursued his explorations some 
 thirty years later, for it was not until after his death that the next 
 great fact in magnetism was discovered, viz., that the variation 
 was not constant in any place, but itself varied from year to year. 
 This discovery we owe to three independent English observers, 
 between 1633 and 1640; but when (Jhamplain was making his 
 survey of the coast, it was thought that, however much the declina- 
 tion might vary in different places, in any one place it was always 
 the same. Had this really been the case tho declination would 
 have materially assisted in determining the position of important 
 points, and under favorable circumstances it might even now be a 
 guide to the mariner, as Basil Hall describes himself, whilst sailing 
 along the coast of Peru, in thick weather, to have found his 
 latitude with considerable accuracy by observations on the dip. 
 But in Champlain's time, when the navigator had no means of 
 checking his dead reckoning, except by an observation for latitude, 
 the declination, had it been constant, would have been a most 
 important addition to his knowledge. It is with this view, rather 
 than with the object of correcting his compass-bearings, and 
 certainly not with the intention of investigating the laws of terres- 
 trial magnetism, that Champlaiu indudes amongst his instructions 
 to mariners : — ** N'oublier souvcat iV apprendre les deolinaisons do 
 la guide aymant en tous licux, qui ^st de sgavoir 9pwbien ell^ 
 
DECLINATION IN NORTH AMERICA. 
 
 >S 
 
 ddoline du m^ridien vers Test et ouest, oo qui pcut servir aux longi- 
 tudes— ayant oes obsoryations et rotournant an mcsmo lieu d'oii vous 
 les aurez prises, trouvant las mesmes doclinoisona vous Ht^auricz ou 
 vous series, soit en rhemisphdro dc 1' Asic ou de la P^rou, ot dc cc on 
 no doit tistro negligent." — He accordingly records several observa- 
 tions with this object, and upon one occasion, whilst endeavoring 
 to identify a river which ho enters (the modern Penobscot) with 
 one described by former navigators as tbo Norombegue, ho says 
 that he cannot be sure of it, as, though tho latitude corresponds, 
 none of them have given the declination — speaking of it much im 
 a modern geographer would of the longitude in a similar case. 
 The coast which he was exploring was indeed peculiarly favorable 
 for such a use of the declination as he found nearly 5° of change 
 of declination in about 1*^ 30' of latitude. 
 
 -i In connection with this subject there arc some curious obser- 
 vations in the notice entitled Intelligence des deux cartes <jco- 
 yraphiques, in the edition of his voyages published in 1813. 
 The smaller of tho two maps, the only one preserved I believe in 
 any copy of the edition on this cuntinent, he describes as being 
 constructed on the true meridian. It may be used, he says, when 
 on the G-reat Bank by placing the needle from 12° to 15'^ or 16° 
 to the west of the north point of the card of the compass — a vague 
 enough determination certainly. But tho other map, which is 
 wanting, must be rather a curiosity. Although the separate ports, 
 bays and capes were alike in each, the general configuration of the 
 shores, he says, is quite different, because this larger map is con- 
 structed to suit a compass made like those of France, where the 
 needle points to the east of north. It seems that tho needle was 
 not usually placed under the north point of the card, though 
 Champlain recommends that as an improvement, but it was fixed 
 about S° 30' to the east of it, so that on the coast of old France 
 the card pointed due north. But when the earlier mariners shaped 
 their course for New France, steering always west by their com- 
 pass, they found themselves after a while several degrees too far 
 south, to their great astonishment. Champlain himself appears to 
 
■1 BARLY RECORDS OF THE MAGNETIC 
 
 have a confuBcd notion that the difference arises from the spherical 
 form of the earth — that if they had been sailing on a plain Hurfucc 
 the compass would have been a correct guide, but that as the sur- 
 face of the earth is curved the compass varies, and the further 
 north you go, and the greater the curvature of a parallel of latitude, 
 the more rapidly the declination varicH. 
 
 To return, however, to Ghamplain's records of observed de- 
 clinations. His method of making the observations is described 
 in his TraiU de la Marine, and it is u rude kind of observation 
 of equal altitudes. Ho placed a board pcrfccUy horizonal in 
 which was a perpendicular pin. In the morning he marked the 
 place of the shadow of the top of the pin on the board, and describ- 
 ing a circle from the pin, he marked the point in the circle where 
 the shadow of tho pin touched it again in the afternoon. The lino 
 bisecting the angle thus formed was due north, and with this he 
 compared his compass. . , . ^. 
 
 Tho localities where the observations were made arc the fol< 
 lowing: — ^ •■■'■'"'• ''■--■ ^"■■" ''-■' •■■■>*--:>■ '.>•..,:; -v!> ^i :■■; . 
 
 Isle Madame, apparently in the entrance to the Gut of Canso, 
 for which he gives lat. 45° 45' ; dec. 14° 50'. • * ■ ' 
 
 Gap La Hevc, which retains its name with a somewhat different 
 spelling, lat. 44° 11'; dec. 16° 15'. i ^^ ,^ r 
 
 Ste. Marguerite, clearly from the description inside of Bigby 
 Neck in the Bay of Fundy, probably tho small bay called Sandy 
 Cove, for which he gives lat. 45° 30' j dec. 17° 16' ; but there 
 appears to be an error of a whole degree of latitude, the real lati- 
 tude being about 44° 30'. The error is probably a clerical one, 
 for he is generally pretty correct in his latitudes. ; • 
 
 Port Royal, in Annapolis Basin, lat. 45° j dec. 17° 32'. 
 
 Isle Ste. Croix, in Passamaquoddy Bay. I do not know that 
 the exact situation of the small island has been ascertained. Lat. 
 46° 20' ; dec. 17° 22'. ^^ . - < 
 
 The entrance to the Norembegue or Penobscot river, lat. 44° ; 
 
 dec. 18° 40'. -':-^■: J:--,: ^' --.V^: .-.?...:-,■.■..:■--..,-: : 
 
 Isle aux Tortues, at the entrance of Kennebec river, lat. 44° ; 
 dec. 19° 12'. 
 
Digby 
 
 Sandy 
 
 it there 
 
 3al lati- 
 
 3al one, 
 
 ^w that 
 Lat. 
 
 |t. 44° ; 
 
 t. 44° } 
 
 DECLINATION IX NORTH AMBUICA. -1| 
 
 Mallebarre.— The name ia still preserved in that of Capo Mala- 
 bar, to the south of Capo Cod ; but the exact locality of the small 
 harbor to which he gives this name is difficult to identify, and the 
 latitude seems incorrect— lat. 10", Jecl. 1H° 40'. 
 
 The only other detenuiontioiis of dcclinntion which I have 
 noticed in Champlain, except the very vnmio one of from 12° to 
 15° or 16° for the (ireatBank already mentioned, is where ho 
 states that the greatest amount ho had observed was 21° in 45° 
 lat. in the 8t. Lawrence. As a trifling difference in the latitude, 
 which is only given in round numbers, would make a considerable 
 difference in the longitude, the locality indicated cannot be satis- 
 factorily ascertained. 
 
 The Jesuit Father Bressani, who seems to have paid more atten- 
 tion to scientific matters than mo.st of his confreres, gives the 
 following declinations : — 
 
 The Great Bank, rather a vugue description, 22° ; Quebec, 16" ; 
 the country of the Hurons, that is, the small peninsula bounded 
 by Lake Huron, Matchedash Bay and Lake Simcoe, 12°. 
 
 I know not upon what ground tho date, 1649, is given by 
 Hansteen. Bressani first came out to America in 1642 and re- 
 turned in 1644 ; he came out again in 1645, returning in 1650; 
 and he says that in all his voyages he observed a similar change of 
 declination. As at the period of the three latter voyages he was 
 maimed from the effects of the tortures of the Indians, and oppres- 
 sed by the recent calamities of his brethren, I should, in the absence 
 of any better information, be inclined to take the date of the earlier 
 observation, 1642. 
 
 It will be perceived that the declinations, as observed by Cham- 
 plain, regularly increased as he proceeded south-west, and, as they 
 thus seem to follow a definite law, we may look upon them as sub' 
 stantially correct. But it is remarkable that the case is now ex- 
 actly reversed along the same coast, the declination decreasing 
 pretty uniformly from Cape Breton to Cape Cod. It is not very 
 easy at first sight to understand what position of the isogonal lines 
 would have given rise to the variation as he found it. The main 
 
10 
 
 EARLY RECORDS OP THE MAGNETIC 
 
 features of a magnetic chart for any period will be best understood 
 by coDcoiving that over obout one-half of the globe the variation 
 is easterly, and over the other half westerly. There are, therefore, 
 two lines of no variation, removed from each other by nearly half 
 of the circumference of the earth. One of these, at which, if you 
 are sailing to the west, you will pass from an easterly to a westerly 
 declination, is now situated in Asia, and is very irregular in its 
 outlines. The other, where you pass from a westerly to an easterly 
 declination, which forms a much more regular. curve, is situated in 
 America, and just touches upon the western extremity of Canada. 
 The lines where the variation is 5°, 10°, 15°, &c., westerly, may 
 be drawn to the eastward of the American line of no variation, 
 and to the westward of the Asiatic one, and following the same 
 general direction; bub as these lines occur at greater intervals 
 near the equator than towards the poles, the lines of equal varia- 
 tion proceeding from its two neutral lines, soon meet towards the 
 equator, after which the next set of lines return upon themselves, 
 and the variation increases as you go to the north or the south. 
 These lines are constantly changing their position, and the ques- 
 tion is, where were they situated in the time of Ghamplain ? 
 Now, as in Champlain's time the declination in France was about 
 8° 30' east, and in sailing to America he passed the line of no 
 declination, and then increased his westerly variation as he ap- 
 proached America, the neutral line which he so crossed would 
 appear at first sight to have been that now situated in Asia. It 
 is by no means impossible that this may have been the case, as 
 we have no means of tracing it over the continent of Asia, from 
 where we find it at the same date in China and Australia; but if 
 so, instead of reaching the Northern Ocean, as now, near Archangel, 
 it must have stretched very far over the Northern Atlantic ; for if 
 on the coast of Nova Scotia he had]been nearer to the American 
 line, the declination would have decreased as he sailed to the west 
 and to the soutli instead of increasing as he found it. This position 
 of the isogoual lines would also correspond very well with the 
 increased declination observed by him in the St. Lawrence, and it 
 
 hj 
 
 h 
 
 as 
 
 II 
 
 a 
 
 iti 
 
 N 
 
DECLINATION IN NORTH AMERICA. 
 
 11 
 
 would not bo inconsistent with the amount of declination assigned 
 to the Great Bank. 
 
 Hansteen, however, in his map of 1600, imagines the American 
 neutral line to have made a loop, somewhat similar to what existed 
 in the Asiatic one at the close of last century, within which Eng- 
 land and Franco were situated, so that the navigators, in proceed- 
 ing to America, would cross the American neutral line where it 
 returns upon itself to the southward, and they would thus pass 
 from an easterly to a westerly variation, which could not be in any 
 other part of the American line. It would be a case analogous 
 to an overturn of geological strata, which appear to rest upon 
 each other in the reverse order of their age. It is true that the 
 position of the isogonal lines as laid down by Hansteen would 
 accord very well with Champlaiu's observations, if the lines were 
 made to run rather more north and south at that point; but 
 the observations upon which he relies for his conclusions arc 
 very few in number, and there is some difficulty in imagining 
 the changes by which the map of 1600 could be converted 
 into that of 1700, particularly when we take into consideration 
 the facts ascertained for intermediate periods, such as Bres- 
 sani's, in whose time the declination in France was 3° 30' i)., 
 the line of no variation, being, as ho says, about the Azores, 
 and the westerly variation decreasing, aa it does now, as you pro- 
 ceed to the south and west from Newfoundland up the St. Law- 
 rence. Whichever solution of this difficulty we may adopt, there 
 is one fact connected with the localities we avj considering which 
 is very remarkable, and which may not be without its significance 
 — that from the earliest observations to the present time there has 
 hardly been any sensible change in the variation in the neighbor- 
 hood of Cape Breton. It appears to be a true neutral point as far 
 as the secular variation is concern-jd. Round this point the line of 
 15° westerly variation has revolved, in the direction of the hands of 
 a watch, through about a quadrant of a circle in about 250 years ; 
 its direction having been in Champlain's time nearly S.S.W. and 
 N.N.E., and at present, W-N-W. apd E.S.E. About the close 
 
 9 
 
12 
 
 EARLY RECORDS OP THE MAGNETIC 
 
 of the last century, though the exact date varies in different locali 
 
 ies, a change appears to have occurred in the direction of 
 
 magnetic oscillation in almost all parts of the world. In Canada, 
 
 the line of no variation seems to have been advancing towards the 
 
 east, during the last century, till almost all our western peninsula 
 
 had easterly variation^ but it has since been moving towards the 
 
 west, till it has almost entirely passed off our boundaries, and the 
 
 declination is now increasing westerly over all Canada. At 
 
 Toronto it has increased from 1° 14' 3", in 1841, to 2° 21' 9", in 
 
 1864, or at the average rate of 3' annually, and at Quebec the 
 
 rate is apparently rather greater. The exact period of the change 
 
 in Upper Canada cannot be well ascertained j at Quebec it appears 
 
 to have nearly coincided with the CDmmencement of this century, 
 
 as may be seen from the following table : — 
 
 1642 16° 00' Bressani. 
 
 1686 15° 30' Des Hayes (Hansteen). 
 
 1785 12° 35' Surveyor General Holland. 
 
 1793 12° 05' do do 
 
 1805 11° 35' Smallefct observed. 
 
 1840 13° 35' Surveyor General Bouchette. 
 
 1860 16° 00' 
 
 We have thus returned to the same amount of declination which 
 
 Bressani observed 220 years ago. 
 
 It is the same all along the Atlantic coast, as may be seen from 
 the following table, extracted from the reports of the United States 
 Coast Survey. 
 
 Cambridge, Massachusetts: — / ;r . . f, , 
 
 DECLINATION. 
 
 1708 9° 00'.... 
 
 1782 6° 48'.... 
 
 1842 9° 34'.... 
 
 ..Earliest recorded observation. 
 ..Smallest recorded. 
 
 Providence, Khode Island : — 
 
 1717 9° 36'.... 
 
 1790 ) go .Q, 
 
 1795 r 
 
 ..Earliest. s^r-t', - ■u^*,.,- ■-' : : 
 ..Smallest. ?■ =^- :; 
 
 1848.: 9° 15'.... 
 
 ;. ,..;... .» ,, ,., 
 
 New York : — 
 
 1750 6° 22'.... 
 
 1789 4° 20'.... 
 
 1845 6° "25'.... 
 
 ..Earliest. 
 ..Smallest. 
 
DECLINATION IN NORTH AMERICA. 
 
 13 
 
 oali 
 I of 
 lada, 
 1 the 
 tsula 
 the 
 [ the 
 At 
 
 n 
 
 in 
 
 I the 
 ango 
 pears 
 tury, 
 
 ■\ ■': ;? 
 
 rhioh 
 
 trom 
 tates 
 
 )n. 
 
 Hatboro', Pennsylvania: — 
 
 DECLINATIOir. 
 
 1680 8* 23' Earliest. 
 
 1790 1° 50' Smallest. 
 
 1850 4° 25' 
 
 From the observations at 18 stations in the United States, as 
 given by C. A. Schott, United States Coast Survey, 1859, App. 
 24, the period of the change in the oscillation varies from 1765 to 
 1815, and the conclusion is drawn that the period is later the 
 further you go South and West, the change of oscillation not hav-. 
 ing yet occurred on the western coast. It is to be observed that 
 that in the same paper the date of the change at Quebv^c is given 
 as 1769, which does not, by any means, accord with tha observa- 
 tions which we have recorded. 
 
 One of the great uses of societies like our own, is to afford op- 
 portunities to persons who have neither the leisure nor the attain- 
 ments necessary to conduct sustained scientific investigations, to con- 
 tribute, nevertheless, occasionally a stray fact, of which the working 
 men of science may take advantage. I had seen only an imperfect 
 notice of Bressani's determinations of declination, f.nd none at all 
 of those of Champlain, which appear to me important, not only 
 from their early date, and the character of the man for accuracy, 
 but also from their remarkable deviation from the law now regulat- 
 ing magnetic variations in the same region. I desired to make this 
 Society the medium of putting them on record io a more accessible 
 saape, than when buried in two rather rare books, and I have taken 
 the same opportunity of treating upon some of the general features 
 of a rather complex subject.