i6o 



M A T H E M A T I C A L and 



this Interval tlie laft micrometer meafure was taken, which 

 is therefore a Uttle doubtful, as the Sun entered another 

 cloud as foon as the artificial contad of the limbs of© and 

 ^ was formed, and before v/e could be certain that the mi- 

 crometer flood in the diredion of the leaft diftance. The 

 firft micrometer meafure is alfo a little doubtful, the mi- 

 crometer having been accidentally moved, while we were 

 reading off the vernier. Both of them however are near 

 the truth; and the other three meafures may be perfectly 

 depended on. 



On a mean of fundry meafures taken backwards ^nd 

 forwards (during the intervals of the other micrometer 



Merc 



no more than 



8''322. The utmoft attention was paid to this point, as 

 one of the mod important obfervations of the whole. 

 The following obfervations were alfo taken of the ap- 



pulfes of the limbs of the Sun, and Mercury's center, 

 to the crofs wires of the tranfit telefcope, viz. 



Appa 



rent 



time 



H. 



m. 



fee. 



3- 



3. 



30 



3- 



3' 



4^ 



3' 



J- 



58 



3- 



6. 



31 



3- 



6. 



^i 



3- 



7. 



ig 



4- 



30. 



34 



4- 



31- 



4 



4. 



3^. 



39 



4. 



33- 



4T 



0's I^owcr liml) at horizontal wire. 

 Q's PftScedcnt limb at vertical wire. 



^ 's Center at vertical wire. 

 0's SiibfetjUcnt limb at vertical wire. 

 ^ 's Center at the horizontal ^vire. 

 0'8 Upjter limb at the horl^iorital wire. 



a. 



0's Lower limb at the horizontal wire. 



0'b Frccedfut limb at ibe vertical. 

 ^ 's Center at tlic vertical. 



0's Upper limb at tlic Iiorizontal wire. 





The other two obfervations of this fet could not be com- 

 pleted, the Sun being again hid under clouds, and appear- 

 ed no more during that day. 



Several more micrometer meafures of the diftance of the 

 neareft; limbs of© and ? might have been taken, between 

 the time of the total ingrefs, and half an hour paft three, 

 when the Sun was firft obicured. But a meafure of this 

 kind, taken carefully once in every 8^ or io\ was judged 

 fufficicnt; and the intervals were employed in attemptinf>- 

 by frequent meafures (as already hinted) to afcertain the 



M 



f\ 



cxadnefs. 



From 



