A voyage of the late King of Sweden and another of mathematicians sent by him : in which are discover'd the refraction of the sun which sets not in the northern parts at the time of the solstice, varition [sic] of the needle, latitudes of places, seasons &c. of those countries : by command of the most serene and most mighty Prince, Charles XI, King of Swedes, Goths and Vandals / faithfully render'd into English.

CHAP. II. An Account of the Longitude of Places. (Book 2)

NOW therefore in the present Year, 1695. in the Month of April, this Charge is committed to me by His most Serene Royal Majesty, that I should undertake the Journey, toge∣ther with the most Illustrious Person, Mr. Andrew Spole, the most ingenious Mathematick Professor in the University of Upsal, and now almost superannuated, my Companion and Associate in the Jour∣ney, and formerly for eleven Years my most pleasant Collegue in this sort of Studies; and that we shou'd omit no∣thing that might conduce for the ma∣king of these Experiments, or any other of this Nature; and above all we were injoined so to hasten our Journey, that we might be in the City Torneo, where

the King's Observation was made, not only some days before the Summer-Sol∣stice, but also that we shou'd go farther to the Northward, where we might see the Sun higher above the Horizon in the North Meridian, by reason of the greater Latitude of the Place: Thus we departed from Upsal with Hearts and Souls resolutely fixed, on the 21st. Day of May, Old Stile, which is used in our Country, at a Season unusual, and not yet fixed, by reason of the Unsea∣sonableness and Rigour of the Weather; and therefore with great Difficulty we passed through Upland, Gestricland, Hol∣singland, Medelpadia, Angirmarnland, and West Bothnia, being for the most part in these last Countries detained by Ice and Snow; especially in passing over Ri∣vers, and Arms of the Sea, which are there in great Plenty, and sometimes so wide, as to be 1000 Paces over; in which not only the Rapidity of the Ri∣vers, and Fierceness of the Winds, but also the Ferry-Boats are to be minded, least they be severed asunder; for two Boats placed at a certain distance from one another, make a Ponton, into which

a Charriot is to be so put with Horses, that the sore-wheels rest upon one Boat, and the hind-wheels on the other; the Oars being fitted on both sides: And in the high way the ground being some∣times slippery, and the Horses and Charriots sticking in dirty Places, crea∣ted us great Trouble, where the Cold being partly dissipated, yet the Earth did not return to its former Solidity and Firmness; for at this Season the Creeks nearest the Shore being hardn'd with Frost and Ice, and many Pines being cut down, and disposed into order, did even then represent a Winter-Journey, the Frost being melted, and thawing near the Bank-side only, so that no body cou'd go any further of the Journey with Safety; and therefore almost all by Land, the way being as yet not well beaten; wherein being tossed by divers Fortunes, at length we happily arrived at Torneo on the 6th. of June, having made a most hazardous Voyage in six∣teen Days, in Charriots, Boats, or on Hor∣ses, and a-foot by turns.

The City Torneo is situated by the Ri∣ver Torneo, rising in Lapland, a very pleasant Place, which the River makes, by parting it self into two Arms, and joining again where it discharges it self into the Sea, from which Island the Citizens assert the City to have received its Name at the time of its Building: But it was founded in this Island in the Year of our Lord M DC XX. when before it was the Seat of Inhabitants, who dwelt some Furlongs from it to the South, where there is still an old Stone-Church; for they have a wooden one in that City, and that curiously built, as generally is usual in other Cities of that Country, not long rebuilded. This City trades chiefly with the Finns and Laplanders, whose Language the Ci∣tizens understand well: In the Winter they likewise give them a Visit with their Ram Deer; and for the Merchan∣dize which they carry with them, re∣ceive others from the Laplanders of equal Value: They have also no incon∣siderable Commerce with the Mosco∣vites, who yearly sell their Goods to them, and part with them at a very

reasonable Price; since those which are brought out of the City Archangel, lie them in less, when the Concourse of the Hollanders is the greatest. The same Evening that we came to Torneo, we ob∣serv'd the Sun above the Horizon, no∣ting the Time by the going of a most exact Clock, which shew'd Minutes and Seconds, which I had for that use, by the Favour of the most excellent Count, and Royal Senator, Nicolas Gyldenstolp, by this at 11 h. 15′, 45″, the Sun was hidden in a little Cloud, passing over it, and appeared that Night no more to us.

On the 7th of June we sound the Al∣titude of the Sun, by two Brass Astro∣labes, exactly divided into Deg. and Min. One of which we wou'd have to be loose, and the other fixed with the Perpendi∣cular, by which the Errors which arise by the Disposition, might be the more easily detected; and by this Means we took Care that the very least difference of them shou'd not escape us; nor was any Calculation made by us, except the Instruments agreed most exactly. The same day in our first Observation, we

found the greatest Altitude of the Sun to be 47°. 48′. On the 8th Day we found the Meridian Altitude to be 47°. 49′. The 9th Day was Cloudy. On the 10th it was 47°. 50′. from which re∣peated Observations, and another more made in the same place at our return, on the 18th of June, when the Suns Meri∣dian heighth had decreased to 47°. 45′. we gathered by an Astronomical Calcu∣lation, the true Motion of the Sun be∣ing consider'd, and the just Parallax added, that the Elevation of the Pole in that City is not so much, as is laid down in some Geographical Tables, especially those of Foreigners, being but 65°. 43′. but no account ought to be had of the Refraction in these Observations, the Body of the Sun being elevated beyond that degree where they cease; we desi∣red truly to confirm these Diurnal Ob∣servations by the fixed Stars; because to those who observe by the Circumpolar Stars, the Altitude of the Pole uses to come out less; and the Winter and Sum∣mer Declinations of the Sun being other∣wise equal, the Hypothesis of the fixed Obliquity of the Ecliptick being granted;

but amongst the more Northerly, at se∣veral Times are render'd inequal by rea∣son of their Refractions; but at that time the Light of the Sun, and its con∣tinual Presence saved us that trouble.

The Latitude of Torneo being found, we were solicitous to find out the true Longitude of it; but seeing that cou'd not be Astronomically obtain'd, by any direct Journey, by reason of the Situa∣tion of Places, we were forced to be sa∣tisfied with the Reports of the Land-Surveyers, who have so exactly describ'd the Measures of the Ways, and the Si∣tuation of all the Countries and Coun∣ties, by the Command of His most Se∣rene Royal Majesty, and because a∣mongst the several Ways of finding out the Longitude of Places, especially at Sea, for which the States of the United Provinces promised so great a Reward to the finder of it, all Eyes being intent upon this Victory, which is not as yet obtain'd: I say, amongst so many ways, no Invention hath yet appeared more excellent than that which is performed by the help of a Pendulum; of which that Noble Hollander, Christianus Con-stantine

Huygens, was the Inventer and Author; a Person, as well for his other Famous Works, as for the sake of this, most worthy of Immortality. And here it came into our Heads to admire the great Constancy of these Portable Clocks, made after that Example, two of which I brought with me from home, accurately distinguished with an Hori∣zontal Pendulum, and divided into Mi∣nutes; but the Third, having also Se∣conds, was added to them at Stockholm. Before our departure I so dispos'd these Two for three Weeks together, to the Motion and Measure of a most correct, exact Pendulum of three Foot, which was such a Rule for me, that I cou'd scarce doubt of their Exactness; since in the whole Journey they went so equally, that they did not differ from one ano∣ther so much as one Minute at the same time. But it moved me more than I can express, in the first Observation at Torneo, when the Suns greatest Altitude, and from thence the true place of the South was known to us, all these Three Clocks wanted only 18 Minutes of this Point; to wit, the Automaton shewed

the Hour of the Day of the Meridian from whence I came, and to which I was joined when I departed at Twelve a Clock, and yet cou'd not rightly show us the Meridian of Torneo; or to agree with it, because that City is judged to be some Degrees more Easterly than Stockholm. For of the Mapps which I now have, one of them, which Aegidius Valkenier put forth in a lesser Form, makes the Longitude of Stockholm 35 Degrees, and 30 Minutes, but of Torneo 40°. 0′. this difference of the Meridians, 4°. 30′. gives the Intervals of Time 18′ Astronomically computed: The other of Fred. de Witt makes the Longitude of Stockholm, 36°. 20′. but of Torneo 41°. 10′. This difference of the Meri∣dians 4°. 50′. makes the measure of Time betwixt them 19′. 20″. A third of Scandinavia, by the same De Witt makes the Longitude of Stockholm 39°. 00. but that of Torneo precisely 44°. 00. which is the greatest, and produces the difference of the Meridians of five Degrees; whence also in Time the difference of Meridians is given 20 Minutes. But which of these two Tables is the latter

and truer is not certain; for in Maps and Clocks the Age of them is not ex∣pressed, on purpose that so they may al∣ways seem to be New; but howsoever it was, these three Maps did not differ so very much from one another, nor from the Scope which I proposed to demon∣strate; for if the first Map please, that agrees exactly with my Clocks, which were so much too slow; and it is plain, that the second differs only in one Mi∣nute, and twenty Seconds; the third differs two Minutes; which equality of Motion and Agreement is certain∣ly to be mightily admir'd in so little and portable Machines; nor did I think that it cou'd by any Accident happen, that for so long a time they shou'd mutually answer one another in the same Laws of Motion; and it is pleasant to be em∣ploy'd in so delightful a Speculation; now therefore, if any shall desire a fur∣ther Scrutiny into it; let him also know that in winding; up the Clock I daily lost five Seconds; for that hath been long observ'd by me; as likewise, that 72 Beats of the Pulse of the Artery, be∣ing Fasting, answer also to one Minute,

when the Body is in Health, and neither bound up with too much Cold, nor in∣flamed with vehement Heat; which Ex∣perience, and that is wonderful, never failed me for fifteen Years together. Therefore, since these five Seconds 12 times reckon'd, make one Minute, the Clock also in twelve Days was too slow by one Minute. Now, because we got to Torneo in sixteen Days, add for those four Days twenty Seconds, that so the number of the lost may be 1′ 20″ which added to 18′ wanting at Torneo, makes the Sun 19′ 20″ which agrees excellently well with the second Maps, as is above showed; they requiring in that time the difference of so many Minutes. But many will be of Opinion, that the ine∣quality of Natural Days doth much op∣pose this Calculation; for the Apogae∣ums and Perigaeums teach us, that the daily Motion in which the Sun returns from one Meridian again into it, is sometimes slower, and sometimes swifter; and that the Anomalies of the Plane of the Ecliptick, lying inclin'd to the E∣quator, may beget some difference of Ascensions; but as these are very little

every Day, and that we use only the Mean, we neglect such a small Time as a thing of lesser Consequence; but when it is necessary we also correct them by Tables of mean Motions made for this Purpose. The Companions of our Journey know that these things are nei∣ther precariously asserted, nor rashly re∣lated by me; and they can honestly certifie, that I have often mentioned this Certainty, not without Admiration; and I will show in the following Pro∣blem, why I have been so long on this Subject, for the sake of those who do not understand it; why the difference of Time in two distant Places ought to be equal to the difference of Longitudes betwixt them.

Let P. be the Pole of the World in this Diagram, A. C. the Aequinoctial Circle, G. E. some Paralle, B. S. the Meridian of Stockholm, D. T. the Me∣ridian at Torneo; therefore because the Sun, by its Diurnal Motion daily runs through the Aequinoctial Circle, A. C. and in it every Hour spends 15 Degrees, and by consequence 360 in its entire

[illustration]

[illustration]

Circumvolution, in the space of 24 Hours. Let these two Places in the Question Stockholm, S. and Torneo, T. be either of them under their Meridians; now let there be taken out of that mid∣dle Map aforementioned, the distance of these Places, 4°. 50′. when the Sun was in the Meridian, D. T. it was 12 of the Clock at Torneo, 19′ and 20″, after that the Sun comes to the Meridian at Stockholm, B. S. at which time it was Twelve a Clock there; but at the same time at Torneo it was Twelve a Clock, 19′ 20″, since Torneo is more Easterly by so many Minutes than Stockholm; and therefore it is manifest that the Arch B. D. and also every one of the Parallels with it to be 4°. 50′. and so much to be the difference of Longitude between Stockholm and Torneo, therefore the Horary difference is equal to the dif∣ference of Longitude, Q. E. D.

This is the true cause why those who go Westerly have longer Days than those who go to the Eastward; for whosoever by going from the East to the West, after some Days passes into a different Meridian, hath a longer Day than if he had stayed in the same Meridian; but it matters not whether the Latitude be the same or different, because in every Lati∣tude it is Noon when the Sun is in the Meridian; wherefore those who go from Torneo to Stockholm have the Day of 24 Hours, and almost 20 Minutes; as on the contrary those who go from Stock∣holm to Torneo lose so many Minutes in a whole Day.

It is manifest from their Journals, that these Variations was the greatest ad∣miration to the Spaniards and Portu∣gueze; for these Sailing to the Philip∣pine Islands with an Easterly Course, almost a Semicircle, gain'd Twelve Hours of the Europeans; but those with a Westerly Course had so many Hours of Day later. Wherefore if two Ships Sailing out of the same Port, go to the same Places, by contrary Courses, the one to the Eastward, and the other

to the Westward, having Sailed a Semi∣circle of the Earth, at their meeting, their Accounts do differ a whole Day from one another; but having Sailed a∣bout the whole Earth, at their return Home will find two Days difference in their Journals. It is clear from Pliny, that the Ancients did not want this Knowledge, who proves it by many Ex∣periments. But especially that those who Sail to the Westward, although on the Shortest Day, can Sail faster than those who Sail in the Night, as having the Sun it self for their Companion.

I thought it necessary to Treat more largely of these very well known Mat∣ters; not that I can, by my own Clocks, prove any certain Longitudes to be found out, but that in Land Journeys, they may be this way most easily ob∣served. But how much we exceed the Skill of the Ancients in this Machine, no body is so Ignorant in Letters as not to understand; for the Ancients had no other way of distinguishing Times, but by Shadows, and Water-Glasses; the more ancient way was used amongst the Chal∣deans and Aegyptians, and at last brought

down to the Greeks; but at Rome they Learned it latelier, as we may see by the same Plinius Secundus: For Scipio Nasica first of all divided the Hours, as well of Nights as of Days, and set up an Hour-Glass in his House in the Year, U. C. 595. which falls out 155 Years before the Birth of our Saviour. So long, says he, the Romans had divisions of Time; but at length in Octavius Au∣gustus's Time, the manner of making Dials was taken from Vitruvius, which afterwards made so great Improvements, that now all Europe, which before had gotten the Victory from the other Parts of the World (whose Inhabitants much admire the Industry of the Europeans) daily strive amongst themselves by new Inventions of this Machine.

How great the Variation of the Nee∣dle is in these Northerly Countries is not to be rashly determin'd; for we by a Meridian Line found in the Town of Torneo, find its Declination from the N. to the W. to be about seven Degrees; for the great incertainty of the Weather hinder'd us to determine it precisely, which seldom permitted us to see the

Light of the Sun, either before or after Noon; and that scarcely except a∣mongst the Clouds; so that a shadow cou'd scarcely be distinguish'd from a Penumbra; tho' it is to be confessed, that the time of the Solstices is least fit for this purpose: For if that matter of moment is to be sought either from the greatest heighth of the Sun, in which the Meridian Line may be had exactly; or from an upright Gnomon perpendicu∣larly erected, that Observation may nevertheless be liable to Error, unless it be frequently repeated in the same place, because the Shadows of the Sun nearest about Noon are sensibly neither increased or decreased: The Sun however in the mean time making its Progress in its own Parallel.