37S 



SURVEY OP THE COAST 



metres ; for which I shall again use the results obtained by 

 me, and stated before : — 



Toises 

 com- 

 pared. 



c 



L 



Tem- Immediate result Reiluction 



pera- of the Temp. — 32°. for 



ture, comparison. tempetatare. 



34°,25 

 36',00 

 37",40 

 38',50 



76",7427475 

 76",7408389 

 76",7386302 

 76' ,7467470 



+ 



2%2 

 4%0 

 5",4 

 6^4 



+ 

 0",00059722 

 O",00108820 

 ",00 146921 

 0",00174145 



Value at SSo. 



76",74334472 

 76",74192710 

 76 ',74009941 

 76",74848845 



76",74429393 



At the time of comparison of the two toises of Lalande in 

 1765, when compared with Bird's scale, the mean of both 

 was 76",734 at the temperature of 6a° Fahrenheit ; and it 

 was stated that it was o",034 longer than when determined 

 by Mr. Graham, of which comparison I know no details. 

 This comparison of 1765 reduced to 33°, by the results of my 

 experiments on expansion, would give the mean of the two 

 toises of M. Lalande, equal to 76",7^^3i63. Whut expan- 

 sion was used tlien, or whether any correction was applied 

 for it, I do not know. I have no knowledge of other com- 

 parisons of the toise, except that which might be drawn 

 froni the determination of the distance over the British Chan- 

 nel, by both French and Knglish measures, in the operations 

 made by General Roy, and by Cassini de Thuiy, for the 

 junction of the Observatories of Paris and Greenwich. 



It is proper that I should observe here, that the toise of 

 Canivet served to make the four toises for the base measur- 

 ing apparatus, which was used in the measurement of the 

 base line of about 43,000 feet on the Marsh ofMoratin 

 Switzerland, made by Mr. J. G. Tralles and myself, upon 

 which the triangulation of Switzerland, begun by us, has 

 been founded. 



Though it is evident that the above comparisons of toises 



