Mr. Bowditch on the transit of Mercury, Nov. 5, 1789. 298 
The observations at Cambridge give the following result. 
App. time. %-@©Par.long. Par.lat. Conj. app. time. 
I. contact 20h. 24/04” 37*321 2282 22h. 39’ 30’+3 
II. contact 20 25 52 3 +309 2 +292 31°9 
III. contact 1 15 44 O -080 3 614 26 °5 
IV. contact 1 17 36 0 :057 3 *619 31 °7 
The mean of these four observations makes the conjunction at 22/. 
39 30’*1, apparent time at Cambridge, corresponding to 3h. 23’ 59’*8 
apparent time at Greenwich. I have preferred finding the conjunc- 
tion at Greenwich from this observation rather than from that at Paris, 
on account of the failure in part of this observation, as mentioned in 
the preceding calculation of the longitude of Cambridge. The lati- 
tude of Mercury given in the above elements was decreased 0-06, 
which appears to be necessary from the observations at Cambridge 
and Philadelphia. 
_ The observations at Philadelphia were as follows. 
App.time. (%-@©)Par.long. Par.lat. | Conj.app.time. 
f. contact 20/. 7’ 39-1 3-481 _— 2"-063 22h. 23' 26"-1 
Il. contact 20 9 29°14 3-472 2-071 07-3 
III. contact O 59 32 °6 O °225 3 °485 13 +2 
IV. contact 1 O01 12 6 O +203 3 *490 70 
The mean of these observations makes the apparent time of con- 
junction 22h. 23'13"*5. The difference between this and 3/. 23' 
59’*8 gives the longitude of Philadelphia by this observation 5h. 0 
46"°3 W from Greenwich. The transit of Venus of June 3, 1769, 
made it 54. 0' 41-0. The total eclipse of June 16, 1806 gave 5h. O! 
36”. The mean of these three observations may be assumed as the 
longitude of Philadelphia 54. 0' 41’-1 W from Greenwich, which dif- 
fers less than a second from the estimate of Mr. Ferrer in vol. vi. page 
359 of the Transactions of the American Philosophical Society, 
37 
