a 
166 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
Two parties were accordingly organized; one composed of Mau- 
pertuis, Clairaut, Camus, Le Monnier, the Abbé Outhier, and Celsius, 
being commissioned to measure an arc in Lapland; and the other, 
composed of Godin, Bouguer, and de la Condamine, a meridian are in 
Peru. 
The polar party landed at the town of Tornea at the mouth of the 
river of the same name in the beginning of July, 1736. They began 
by exploring the river, and finding that the course of its valley is 
nearly north and south and flanked on either side by high mountains, 
they resolved to establish the stations of their triangulation on these 
mountains. The tops had to be cleared of timber, and the signals 
were constructed in the form of cones composed of several large trees 
denuded of their bark, their white surfaces being thus visible at a 
distance of 10 or 12 leagues. The angles were measured with a 
quadrant having a radius of 2 feet, whose accuracy they verified by 
measuring all the angles at a station that close the horizon. The 
three angles of each triangle were also measured, and also check 
angles, which were sums or differences of necessary angles at a 
station. 
The measurement of the angles occupied 63 days, and on September 
9 the party reached Kittis, the most northerly station, and made 
preparations for their astronomical work. ‘Two small observatories 
were built, one of which contained a small transit instrument and a 
clock, the former instrument being set up exactly over the center of 
the station. The transit instrument was used in determining’ time 
and the azimuths of the two stations visible from the observing 
station. The other observatory contained a zenith sector having a 
telescope 9 feet in length which was used in determining the difference 
of the latitude of the two terminal stations. Observations of 0 
Draconis, which passed near the zenith of the place, were taken 
between October 4 and 10. The party then proceeded to Tornea and 
commenced observations on the same star on November 1, finishing 
on the 5th. Their instrument gave the difference of zenith distance 
of the star as observed at the two stations; this difference, corrected 
for aberration, precession, and nutation, gave the amplitude of the are 
57’ 26:93.’ 
The final operation was now the measurement of the base line. 
This had been intentionally postponed until winter, as its site had 
been so chosen that the greater part of its length lay along the River 
Tornea, its extremities only being on land. The frozen river. would 
thus afford a level surface upon which to carry on their measurement 
The party had brought with them from Paris a standard toise, called 
afterwards the ‘‘Toise of the North,” which, with another taken by 
the Peruvian party, had been carefully adjusted to be at standard 
length at 14° Reaumer. By careful comparison with this standard 
