562 



PHILOSOPHICAL TRANSACTIONS. 



[anno 1732. 



Ahitiules observed by Mr. Bradley. 



The 1st and 6th columns, of the preceding Tables of Observations, are 

 copied from the minutes as they were set down at the time. The divisions of 

 the wooden instrument being not exact, Mr. H. found it necessary to make a 

 Table to correct them by, which was done partly by measuring with compasses, 

 and partly by examining them against those of another instrument. The cor- 

 rections are every where to be subtracted from the angles observed, and the 

 errors of 1° 3;/, occasioned by the misplacing the 2d speculum, in all the for- 

 ward Observations of Sept. 1, being of the same kind, are joined with them, 

 in the 7th column of the Tables of those Observations. The last column con- 

 tains the differences between the observed Altitudes, corrected by the aforesaid 

 Table, and the Altitudes as they ought to have appeared by the computations. 

 Among them there are two or three which so much exceed any of the rest, that 

 for that reason they seem to be rather owing to mistakes, in counting the mi- 

 nutes on the instrument, or the time by the watch, than to the Errors of the 

 Observations. 



The greatest part of the altitudes were taken by a horizon not clear of land, 

 and by that means not always so readily distinguishable. The observers were 

 all persons quite unaccustomed to the motion of a ship at sea, which in this 

 case was generally very great and quick, the vessel we were in being only of 



