XXTL. XLVI.] PHILOSOPHICAI, TRANSACTIONS, QJ 



He judged they rose about one degree above the horizon, and that their lights 

 were strong enough to have been seen much farther. 



From Essex Mr. R. was informed, that the persons on Tiptery-heath saw 8 or 

 Q rockets very distinctly, at about half an hour past 8 ; and greatly to the east- 

 ward of these 5 or 6 more. The gentlemen from Godmarsham in Kent having 

 waited till above half an hour past 8, without being able to discern any rockets, 

 they fired half a dozen ; which, from the bearings of the places, were most pro- 

 bably those seen to the eastward by the persons on Tiptery-heath ; and if the 

 situations, as laid down in the common maps are to be depended on, at about 35 

 miles distance. 



The engineer being of opinion that he could make some rockets, of the same 

 size as the former, that should rise much higher, Mr. Robins directed him to 

 make half a dozen. These last were fired the 12th of October following, from 

 the same place, and in general they rose nearly to the same heights with the 

 foregoing ; excepting one which was observed to rise 6qo yards. The evening 

 proved very hazy, which rendered it impossible for them to be seen to any consi- 

 derable distance. 



Among some rockets fired in the last spring, there were two made by Mr. da 

 Costa of about 3-l inches diameter, which were observed to rise, the one to about 

 833, the other to QIS yards. At a second trial, made some time after, there 

 was one made by Mr. da Costa, of 4 inches diameter, which rose to 1 1 QO yards. 

 The last trial was made the latter end of April 1750, when 28 rockets were fired 

 in all, made by different persons, and of different sizes, from 1^ inch diameter 

 to 4 inches ; the most remarkable of each size were as follows : one of 1 -^ inch 

 rose to 743 yards ; one of 2 inches to 659 ; one of 2^ inches to 880 ; another 

 of the same size, which rose to IO71 ; one of 3 inches to 1254 ; one of 34. 

 inches to llOQ; and one of 2 inches, which, after having risen to near 700 

 yards, turned, and fell very near the ground before it went out. These were all 

 made by Mr. da Costa. Besides these, there was one of the rockets of 2-l inches 

 in diameter, which rose to 784 yards, and another made by Mr. Banks of the 

 same size to 833. 



After allowing for possible errors, it still appears certain that several of these 

 rockets rose to 1000 yards, one to 1 100, and another to 1200 yards, or double 

 of any of those fired in the Green Park. 



Several Papers concerning a new Semi -metal, called Platina. Communicated to 

 the R.S. by Mr. Wm. IVatson* F.R.S. N° 496, p. 584. 



* As this appears to have been the first printed account of this new metal, it has been judged to 

 be due to the memory of those who communicated it to reprint it nearly in the original form. 

 VOL. X. O 



