3Q4 PHILOSOPHICAL TRANSACTIONS. [ANNO iGjJ, 



distance of the head of the comet from Algol correct by refraction was 8° I9', 

 from Mirach, 19° 37'- 



And admitting with Mr. Hevelius the place of Mirach now in "f 21° 40' 34'', 

 with north latitude 25° 57\ its distance from Algol will be 23° 42' 40", and 

 the place of the head of the comet in y 14° 48^', with north latitude 17° 8'. 



At 15^ 28*" I state the correct distance of the comet's head from Capella 31°, 

 from Alameck 11° 40'; and therefore its true place in y 14° 504-', with north 

 latitude 17° 6' 25''^; agreeing very well with the place derived from the former 

 distances from two other and different stars. 



The tail was not, it seems, directly opposite to the sun ; for the sun's place 

 was now y 30° 7'; but the comet being in 14° 47' of the same sign, that is 

 l** 40' in consequence of the sun, the tail ought, if it had been exactly opposite 

 to the sun, to have lain in consequence of the head ; but the knee of Cassiopea 

 is now in y 13° 24' in antecedence of the comet, whose tail lay not therefore 

 in consequence, but in antecedence of the line passing through its head and the 

 sun, at about an angle of 10". 



Next night, being that following the 23d of April, about -|- of an hour after 

 2 1 saw its tail, which appeared much shorter than last morning through a break 

 of the clouds ; which soon after opening wider I saw the head too, and hasting 

 I measured its distance. April 23 at 14*" 51"^ p. m. from Mirach 21° 9'; but 

 before I could get the plane of the sextant to Algol, the clouds came over the 

 comet again, and I could see it no more. 



Hence, and from a coarse observation of it sent me by an ingenious friend^ 

 I found its motion was direct, and its latitude decreasing. 



Jin jiccount of some Books. N° 135, p. 875. 



I. The Natural History of Oxfordshire, being an Essay toward the Natural 

 History of England. By Robert Plot,* LL.D. Printed at the Theatre in Ox- 

 ford, 1677, in fol. 



* Robert Plot, author of the well-known History of Oxfordshire, &c. was, according to the au- 

 thors of the General Biographical Dictionary, 8vo. born of a genteel family, in l641, at Sutton-Barn, 

 in Kent, and educated at the Free-school of Wye, in the same county. In l658 he went to Mag- 

 dalen Hall in Oxford} took the degree of Bachelor of Arts in 166I, and that of Master of Arts in 

 1664, and both the degrees in law in 1671. He afterwards removed to University College. Being 

 a ver)' ingenious man, and particularly attached to natural history, he was elected a Fellow of the 

 Royal Society, and in 1662 was chosen one of the secretaries. He published the Philosophical 

 Transactions from No. 143 to No, 166 inclusive. In l683, Elias Ashmole, Esq. appointed him the 

 first keeper of his museum 3 and about the same time he was nominated by the vice-chancellor the 

 first professor of chemistry in that university. In l687 he was made secretary to the Earl-marshal, 

 or Comt of Chivalry, which was then renewed, after it had lain dormant since the year 1^41. In 



