4 5 ° The Account of a 
Sennen. This station is in the north-west corner of a field 
belonging to Mr. Williams. The field may be easily found, 
as there is no other spot near the town of Sennen, from which 
the Longship’s Light-house, Pertinney, and St. Buryan, can be 
seen. 
Karnminnis, near St. Ives. The station on the top of this 
hill, may be found from the following measurements : 
The station from 3 large f 8 
moor-stones, south of< 11 
8 from the south 1 
0 north > stones. 
1 west j 
the hedge. \_ 14 
St. Buryan. The station is in a field adjoining the town, 
and by the side of the Penzance road. It is 84^ feet from the 
stile, and 48 feet from a large stone in the northern hedge. 
This stone is 81 feet from the stile ; the station, this stone, and 
Chapel Karnbury, being in a right line. 
art. vi. Demonstration of M. de Lambre’s Formula in the 
Connoissance des Temps of 1 793, for reducing a Distance on 
the Sphere to any great Circle near it, or the contrary. By 
Nevil Maskelyne, D. D. F. R. S. and Astronomer Royal. 
Put A= angle subtended by two terrestrial objects; a == the 
same reduced to the horizon ; H, h the two apparent altitudes : 
if either is a depression, it must be taken negative. 
By spherics, c, A = c, a . c, H . c, h -j- s, H . s, h. 
Put A = a -j- da, where d a signifies A — a, and not their 
differential. 
By trigonometry c, A = c, a.c,d a —s, a . s, d a = c, a x 1 — vs, da 
— s, a . s, d a = c, a — c, a x 2 $*,-§■ d a — s, a . s, d a (by theo- 
