IN SOUTH AMERICA. 



24^ 



On reaching Para and bidding adieu to the woods of the Amazons, we fancied our- 

 felves at once tranfported to Europe. We found here a large city, rectilinear ftreets, 

 pleafant houfes, moft of them rebuilt of ftone and brick within the laft thirty years, 

 and churches of magnificent appearance. 



The commerce of Para direft with Lilbon, whence a fleet of merchant fhips arrives 

 every year, enable thofe of the place whofe circumftances are eafy, to provide them- 

 felves with all the comforts of life. They receive European commodities in exchange 

 for the produce of the country 5 fome little gold-duft brought from the interior of the 

 Brazils, and all the various ufeful articles as well from the rivers which fall into the 

 Amazons, as from that river itfelf, fuch as clove-wood and the black nutmeg, falfapa- 

 rilla, vanilla, fugar, coffee, and in abundance cocoa, which is the currency of the 

 country, and at the fame time its ftaple. 



Probably the latitude of Para had never before been obferved on fhore, for when I 

 arrived there I was confidently told I was under the line. Fritz's map places this city 

 in lat. 1° o' S. By repeated obfervations, all of them agreeing, I found it to be 1 ^ 28' S. 

 which latitude differs immaterially from that laid down in the Map of Laet, one, 

 not to my knowledge followed by any after-geographers. In the New Portuguefe 

 Traveller it is laid down in lat. i ^ 40' S. As to the longitude I am enabled to fix it 

 with nicety by the eclipfe of the moon, which I obferved on ifl Nov. 1743, and by 

 two immerfions of the firll fatellite of Jupiter, on the 6th and 29th December, in the 

 fame year. In the interval of my procuring correfponding obfervations in fome fpot 

 the longitude of which is authenticated, as there were none effected at Paris, I calcu- 

 lated the difference of the two meridians of Para and Paris to be three hours, twenty- 

 four minutes. I omit the obfervations I made on the variation and dipping of the 

 needle, and on the tides, which are rather irregular at Para. 



A more important obfervation, and which immediately relates to the fi'gure of the 

 earth, the chief objeft of our voyage, was undertaken by me ; I mean the afcertain- 

 ment of the length of the pendulum to give mean time, or rather the difference of the 

 length of fuch pendulum at Quito and at Para, one of thefe cities being on a level with 

 the fea, the other from fourteen to fifteen hundred toifes above its level, and both 

 under the equinoctial line ; for a degree and a half here is of no confequence. In this 

 experiment I employed a pendulum twenty-eight inches long, more minutely defcribed 

 elfewhere, which continued its ofcillations vifibly for more than twenty-four hours and 

 with which I had made a great number of experiments at Quito, and on Mount Pi- 

 chinchi feven hundred and fifty toifes above the level of Quito. The refult of nine 

 experiments made at Para, the two moft diftant of which varied but three ofcillations 

 in 98,740, I found that my pendulum vibrated from thirty-one to thirty-two times 

 oftener than at Quito, and from fifty to fifty-one oftener than on Pichinchi. From 

 thefe experiments I concluded that under the equator, two bodies, one of which 

 fhould weigh one thoufand fix hundred and the other one thoufand pounds, at the fur- 

 face of the fea, being tranfported, the one to the height of one thoufand four hundred 

 and fifty, the other to a height of two thoufand two hundred toifes, would each of them 

 lofe a pound of their weight, as, or nearly, would be the cafe if the fame experiments 

 were made under the parallels of 22^ and 28° according to the tables of Sir Ifaac 

 Newton, or, judging from the actual experiments made under the equator, and in 

 various parts of Europe, under the parallels of 20^ and 25^. The numbers . I 

 have cited are merely approximate, and I claim the privilege of making what flight 

 alteration may be neceffary, after applying the fuitable equations, when I publifh the 

 detail of my experiments on the pendulum. 



VOL. XIV. K K During 



