VOL. XLVI.] PHILOSOPHICAI, TRANSACTIONS. 66\ 



there were 3 which rose to 74°; and that in the last great flight of rockets, said 

 to be of 6000, the crest of the arch, formed by their general figure, was ele- 

 vated about 84°. 



The distance of this statical from the building in the Green Park, is 4000 

 yards, according to the last great map of London ; and hence it appears, that 

 the customary height, to which the single, or honorary rockets, as they are styled, ■ 

 ascended, was near 440 yards; that 3 of these rose 526 yards; and that the 

 greatest height of any of those fired in the grand girandole, was about 6 1 5 yards, 

 all reckoned above the level of the place of observation, which is near 25 yards 

 higher than the Green Park, and little less than 1 5 yards below the chests whence 

 the great flight of rockets was discharged. 



It seems then there are rockets which rise 600 yards from the place whence 

 they are discharged; and this being more than a third part of a mile, it follows, 

 that if their light be sufficiently strong, and the air be not hazy, they may be 

 seen in a level country at above 50 miles distance. 



The observations on the single rockets are sufficiently consonant to some expe- 

 riments Mr. R. made about a fortnight before; for then he found that several 

 single pound rockets went to various heights between 450 and 500 yards, the 

 altitude of the highest being extremely near this last number, and the time of 

 their ascent usually short of 7"- 



But though from all these trials it should seem as if good rockets of all sizes 

 had their heights limited between 400 and 600 yards ; yet he believes that they 

 may be made to reach much greater distances. For he lately saw a dozen of 

 4 lb. rockets fired; the greatest part of which took up near 14* in their ascent, 

 and were totally obscured in a cloud near 9 or 10' of the time; so that the mo- 

 ment of their bursting was only observable by a sudden glimmering through the 

 clouds; and as these rockets, during the time they were visible, were far from 

 moving with a languid motion, the extraordinary time of their ascent must have 

 been attended by a very unusual rise. 



Extract of so much of Don Antonio de Ulloa's Account of his Voyage to South 

 America, as relates to the Distemper called there Vomito Prieto, or Black 

 Fomil. TransL from the Spanish by W. IVatson, F.R.S. N*^ 492, p. 134. 



The city of Carthagena in America is situate in 10° 25' A8\" of north latitude. 

 The weather there is always sultry hot. A thermometer constructed by Mons. 

 de Reaumur gave, on the 19th of November 1735, one of their winter months, 

 the degree of the warmth of the air 1025^ divisions; and this with little varia- 

 tion, both night and day. The greatest height to which the spirit ascended at 

 Paris the same year, by a thermometer graduated in the same manner, was 10254^; 



