l62 PHILOSOPHICAL TRANSACTIONS. [aNNO I667. 



he not been unfortunately slain in his late majesty's service. He had a treatise 

 on optics ready for the press, but though I have used my utmost endeavour to 

 retrieve it, it has not been with success. The instrument is small, not exceed- 

 ing in weight, nor much in bigness, an ordinary pocket watch, exactly marking 

 above 40,000 divisions in a foot, by the help of two indexes ; the one showing 

 hundreds of divisions, the other divisions of the hundred ; every last division 

 in my small one containing -r-V of an inch ; and that so precisely, that as I use 

 it there goes above 24- divisions to a second. Yet I have taken land angles 

 several times to one division, though it be very hard to come to that exactness 

 in the heavens, because of the swift motion of the planets. Yet to remedy 

 that, I have devised a rest, easy to be made and used. 



Mr. Hook also announces (p. 459), that he has two or three ways of mea- 

 suring the diameters of the planets to the exactness of a second, by the help of 

 a telescope ; and of taking the position and distances of the fixed stars from 

 each other, when this does not exceed two or three degrees. 



Of the Nehulosa in the Girdle of Andromeda ; and the extraordinary 

 Star in the Nech of the Whale. By M. Bulliald. N" 25, p. 459. 



January 1667, the nehulosa in Andromeda's girdle, which may be seen by 

 the bare eye, appeared much more obscure than the year before. In the 

 months of February and March I did not see it. 



January 20, 1667, at night, 6 h. 30 m. the sky being pretty serene, the 

 star in the neck of the Whale approached to the size of a star of the sixth 

 magnitude, and grew afterwards larger. For, Feb. 12, 6 h. 30 m. it equalled a 

 star of the fourth magnitude at least. And Feb. 24, 7 h. was equal to one of 

 the third magnitude, shining very bright. 



Feb. 26 and 27 it appeared still to increase. 



M. Hevelius also observes concerning this star ; viz. Jan. 23, I found a 

 little star of the sixth or seventh magnitude, about the same place where the 

 said new star used to appear. But it then seemed to me not the genuine new 

 star, but another preceding the new ; the longitude of which has been defined 

 by me in Mercurius in Sole visus, Aries 25° 43' 3''', and the latitude 14° 4l' 

 32'^, south. Anno 1660, Feb. 2, it appeared very bright, and when the 

 moon shone, of the size of that in the mouth of the Whale ; from which time 

 I always observed it to grow larger. March 13, I still found it extremely 

 bright, but could not accurately determine its magnitude by my naked eye, 

 because of the vivid crepuscle, and the lowness of the star. 



