186 PHILOSOPHICAL TRANSACTIONS. [aNNO 1787- 



XII. Observations of Miss HerscheVs Comet, made at Chislehurst, in yfugust 

 and September, 1786. By the Rev. Francis JVollaston, LL. B., F. R. S. 

 p. 5o. 



The comet of August last, having afforded Mr. W. an opportunity of putting 

 to some test the system of wires, a description of which he had laid before the 

 R. s.,* he thought it might not be improper, as a sequel to that paper, to give 

 an account of the observations made with it on this occasion ; which will serve 

 to show what dependence may be had on observations made with such an instru- 

 ment. The telescope to which he applied it was an achromatic object-glass of 

 Dollond, .of 16 inches focal length, and 2 inches aperture, with a Ramsden's 

 eye-glass> magnifying about 25 times, mounted on a very firm equatorial stand : 

 with this, which takes in 2° of a great circle, he compared the times of the 

 comet and such stars as lay convenient, as they severally passed the centre wire 

 and other adjoining wires ; making occasionally a diagram, or drawing of their 

 appearance in that telescope. 



In this list of observations are set down the times, with the neighbouring 

 stars, and the differences of right ascension and declination. During the whole 

 time, the comet was invisible to the naked eye, and without any tail. Its ap- 

 pearance was so very similar to the nebula N° 3 in Messier's Catalogue inserted 

 in the Connoissance des Temps for 1784, and some other years, as scarcely to 

 be distinguished from it when in the telescope together ; though it certainly had 

 a brighter spot in the centre. 



XIII. Of a Thunder-Storm in Scotland ; with some Meteorological Observations. 

 By Patrick Brydone, Esq., F. R. S. Dated Lennel-House, near Coldstream, 

 December 20, 1786. p. 61. 



Tuesday, July IQ, 1785, was a fine soft morning, thermometer at ten, 68°; 

 about 11, clouds began to form in the south-east ; and between 12 and 1 there 

 were several flashes of lightning, followed by rolling claps of thunder, at a 

 considerable distance. Soon after however Mr. B. was suddenly alarmed by a 

 loud report, for which he was not prepared by any preceding flash : it resembled 

 the firing of several muskets, so close together, that the ear could hardly sepa- 

 rate the sounds ; and was followed by no rumbling noise like the other claps. 

 Soon after he was told that a man and 2 horses had been struck dead by the 

 thunder, at a small distance from his house. Mr. B. immediately set out, and 

 arrived on the spot in less than half an hour after the accident. The horses 

 were still yoked to the cart, and lying in the same position in which they had 

 been struck down ; but the body of the young man had been already carried off 



• See vol. 7S, p. 346. 



