Proceedings of the Royal Society of Edinburgh. 395 



excepting in the case of certain imperfectly transparent and opa- 

 lescent fluids, there never was the slightest trace of a reflected tint 

 similar to that which might have been expected, had the Newtonian 

 theory been true. 



2. Notice respecting the Determination of the Geographical 

 Positions of the Village of Chamouni, and of the Con- 

 vent of the Grand St. Bernard. By James D. Forbes, 

 Esq., F.R.SS.L.&Ed. 



The author undertook the determinations of these positions at 

 the suggestion of Professor Gautier of Geneva, who informed him 

 that they had not been fixed by any direct observations. The 

 great discrepancies of the best maps of the Alps in laying them 

 down, confirm this opinion ; and the author has quoted- the lati- 

 tudes and longitudes, given by the best authorities, at the end of 

 his paper. 



The new determinations give for the positions,— 



Latitude. Long. E. of Genera. 



Chamouni, 46' 55' 64" . . . 27" 25 



St Bernard, .... 45" 50' 16" . . . 28" 19 



The latitudes were determined by successive altitudes of the 

 pole star, taken with an altitude and azimuth circle, upon Captain 

 Kater's construction, the circles being 4^ inches in diameter, and 

 divided to J 5". The position of St. Bernard is the best deter- 

 mined, eight altitudes of the pole star having been taken, the re- 

 sults of seven of which agree closely. 



The longitudes were determined chronometrically, in thejirst 

 place, by comparisons with the Geneva Observatory clock, and in 

 the second, by the time at the two places, calculated from altitudes 

 of the sun taken with the instrument just mentioned. Though 

 the rate of the chronometer was wonderfully steady, considering 

 the shocks to which it was exposed, the author does not conceive 

 that the longitudes are determined with very great precioion. 



Dec, 17. — Professor Russell, Vice-President, in the Chair. 



The time usually employed in the ordinary business of the So- 

 ciety having been occupied by a discussion on extraordinary aflfairs, 

 the reading of the communications announced for this meeting 

 deferred. 



