26 



ON Comparative 

 tions and refractions it undergoes in the process. As the 

 three kinds of micrometers, jast described, are so completely 

 different from each other, in their construction, adjustment, 

 and mode of mensuration, I consider them as fully sufficient to 

 make an experiment on the probable consistency of the results 

 which may be obtained from different good micrometers ; and 

 shall now proceed to give a detail of the actual observations. 



Observations ,*„, O r*- /-\ Semidiameters ofO,as givei 



of the sun's I7y*> o. Ur. (^ . in the Nautical AlnraRack. 



of the sun's 

 diameter. 



August 26, D. O. G, Micr. 7 15'. 53",835 7 , ., .„„ .^ 

 Wire Micr. . . j 15'. 54",03 $ ^^ ' ^"^ '*^- 



Sept. 3, D. O. G. Micr. . .>. 15'. 56",01. 



Wire Micr il5'. 55",9 



A set of ten, all agreeing f C. 15' 55" 4 



on the sextant, on ti^ /" • » • 



limb, and arch of ex- \ 

 cess Jl5',55",0 



Sept. 11, I.T.S. V. 



D.O. G. Micr. 3.5.1. 19 

 Error of 



3.5.1. 19.^ 15'. S6",54\ 

 V. 4-2 / I 



R. D.V yi5'.57",f, 



icr. 15.41.1 15'. 57",1 i 

 '. + 3'. . . .J 15'. 58",0 J 



G. S. Dr.W. Mi 

 Sextant, 15*. 55 



Sept. 17, R. D's. 



Dr.of 0. 15. 43. W. Micr.") 15'. 58",3 \,,, .^„^ 



Sextant, . j 15'. 59",3 j ^^ ^^ '"'' 



Sept. 27, 



D. O. G. Micr. 



Wire 



Sextant 



^7, 



G. Micr. ..... .7 16'. 1",857 



Micr .>16'. l",95Vl6'. 1",7. 



It +3", 3 16'. 1",703 



