6l4 ' VHILOSOPHICAI- TRANSACTIONS. [aNN0 1742. 



Motion of the same for the interior contacts 13' 4" 



Hence, the time of the interval from the ^ to the middle 14 32 



Of i the exterior transit 2° 14 22 



Of 4- the interior transit 2 J 2 30 



Hence, the first exterior contact of the limbs, Oct. 25, morn S'^ S'i"" ig« 



The first interior contact 8 34 11 



The nearest approach of the centres, or middle 10 46 41 



The last interior contact, afternoon O 59 11 



The last exterior contact, or end of the transit i 1 3 



This computation is made from tables * which give the ascending node of 

 Mercury at the time of this transit 6' 17" too forward, according to the result 

 of very accurate observations made of that in the year 1723, by Dr. Halley, 

 Dr. Bradley, and Mr. Graham. Therefore making the calculation with this 

 correction of the place of the node, the times of the several circumstances of 

 the transit will be as follows : 



The first exterior contact 8*" 29" 21' 



The first interior contact 8 31 5 



The nearest approach of the centres 10 46 6 



The last interior contact 1 1 77 



The last exterior contact 1 2 51 J afternoon. 



This transit may be very aptly compared with that which happened on the 

 24th day of October l6g7;-|- as happening at the end of a remarkable period 

 in Mercury's motion, by which he is nearly in the same situation, with respect 

 to the sun, at every completion of it. Dr. Halley, in his series of moments, 

 in which Mercury is joined to the sun, &c. published in the Philos. Trans. 

 N° 193, makes the middle of this transit at 11"* past 6 in the morning the 24th 

 day, or the 23d day at IS** 1 ]" p. m. and the distance of the centres of the 

 sun and Mercury 1 0' 4". 



Only the egress of Mercury, in the transit of 1 697, could be observed in 

 Europe;! which was done at Nuremberg in Germany, by Mr. Wurtzelbaur, 

 and at Paris by M. Cassini: at Greenwich clouds prevented it. At Nuremberg 

 Mr. Wurtzelbaur observed Mercury to go off the sun's disk § at 8*^ 45-^™ 

 mane, about 734^ degrees from the vertex of the sun to the right hand; and 

 M. Cassini observed the same accurately at B^ 10"" 24* mane; therefore from 



* Philos. Trans. N" 386. — Orig. 

 + Mean period 46" years Id. oh. 43' 42''. — Orig. 

 J Flamsteed's Hist. Coelest. lib. ii, fol. 32. — Orig. 



§ Vertex to the right, it says, a nadir solis ad dextras; but it is a manifest mistake, as any one on 

 trial may find. — Orig. 



