24 



Introdtiction to the Sixth Sectio?i 



From March 27 to April 7 +0"-0040 t. cos 8 

 April 8 — May 19 ± -0226 t. cos 8 

 May 23 — May 25 + -0551 /. cos 8 

 May 27 — Nov. 14 +0 -0097 /. cos 8 

 Dec. 1 — Dec. 31 ±0 -0109 t. cos 8 

 where t denotes the number of seconds before the culmination ; 

 and the upper sign is to be applied for the eastern, the lower 

 one for the western position of the circle. 



The same observations have decided that gravity does not 

 act on the horizontal wires ; for the observations made at the 

 two extremities, and reduced to the meridian, always very 

 nearly agreed with those made in the middle ; and the mean of 

 the frequent trials of this kind, occurring in the journal, do 

 not show the least trace of a flexure by gravity. 



The difference of two verniers from four I have determined 

 by a set of readings, which were repeated three times, and 

 freed from the effect which the temperature might produce by 

 acting unequally on the circle and the alhidade, by allowing 

 always at least half an hour to elapse between the placing and 

 reading off* of the circle. 



The 



