VOL. LIV.] PHILOSOPHICAL TRANSACTIONS. I69 



dicate them even from the smallest censure, which they do not appear to deserve? 

 At the same time I flatter myself, that the learned editor of the Connoissance 

 des Mouvements Celestes, and also the friends of the late illustriovis Abbe de la 

 Caille, who I believe was inadvertently the first author of this mistake, will take 

 no offence at my endeavouring to clear up a point, which they, doubtless for 

 Ivant of having given sufficient attention to, seem to have mistaken; since, 

 truth being the common object of all our pursuits, we ought candidly to accept 

 as well the assistance we receive from each other for bringing us into the right 

 road, when we happen to have strayed from it, as for helping us forward on our 

 journey. 



LVII. Astronomical Observations made at the Island of St. Helena. By Nevil 

 Maskelyne, M. A., F.R.S. p. 348. 



These are observations chiefly of the moon and stars transiting the meridian 

 and wires of the telescope, &c. also of the setting sun. Not of material use 

 now at this time. 



In the conclusion Mr. M. takes occasion to notice a former remark of Mr. 

 Short's on some of his preceding observations. " I must not pass by this occa- 

 sion, says Mr. M. without taking notice of some remarks, which Mr. Short 

 passes on my method of examining the going of the clock, by observing stars 

 setting behind a hill, with the telescope of the equal altitude instrument; (vide 

 Mr. Short's account of Mr. Mason's paper concerning the going of Mr. Elli- 

 cott's clock at St. Helena, Phil. Trans, vol. lii. part 1. p. 540). Mr. Short's re- 

 presents Mr. Mason, as saying in his paper, that I proposed making use of the 

 equal altitude instrument to determine the regularity of the motion of Mr. EUi- 

 cott's clock, by observing the vanishing of the stars out of the field of the te- 

 lescope, an expression not contained in Mr. Mason's paper, who is only speaking 

 of our observing stars setting behind a hill, at the distance of a quarter of a mile, 

 in the same part of the field of the equal altitude instrument. Had we proceeded 

 in the method supposed in the remarks, no doubt the observations would have 

 been liable to considerable inaccuracy ; but as we used the telescope of the equal 

 altitude instrument, only to assist the sight in observing the stars setting behind 

 the hill, we were liable to no other error than what might arise from the small 

 alterations of the instrument, arising Irom the changes of heat and cold, mois- 

 ture and dryness, seen from the distance of the top of the hill, which will easily 

 be allowed to be quite insensible. And indeed how otherwise could the observa- 

 tions, contained in Mr. Mason's paper, agree so well together as they do ? A 

 circumstance alone sufficient to create a suspicion of the objection being ill 

 grounded. The reason of Mr. Mason and myself always observing the stars to 

 vanish behind the hill, in the same part of the field of the telescope, that is, 



VOL. XII. y^ 



