Hi- 

 hydrogen, or as deriving its peculiarities from au inflammable vapour. 

 To this new gaseous compound much of the illuminating power of 

 coal and oil gas is to be attributed. 



An Account of Experiments to determine the Acceleration of the Pen- 

 dulum in different Latitudes. By Captain Edward Sabine, of the 

 Royal Regiment of Artillery, F.R.S. and F.L.S. Read March 8, 

 1821. [Phil. Trans. 1821, p. 163.] 



The clocks and pendulums used in these experiments are the pro- 

 perty of the Royal Society, and were prepared by their direction, 

 under the superintendance of Captain Kater, whose description of 

 them is quoted by the author at the commencement of this paper. 



The experiments were made during two voyages of discovery in 

 search of a North-west Passage, the first in 1818, and the second in 

 1819 and 1820; and Captain Sabine details in succession the pro- 

 ceedings at each station, where an opportunity was afforded of land- 

 ing and setting up the clocks ; and concludes by recapitulating the 

 number of vibrations made by each pendulum in the different latitudes 

 in which it was tried, and by stating the deductions regarding the 

 figure of the earth which follow from the acceleration thus deter- 

 mined. In the first voyage, the number of vibrations was ascertained 

 at two stations only ; namely, at Gardie House on the Island of 

 Brassa, and on Waygat, or Hare Island, on the West coast of Green- 

 land ; the latitude of the first being 60 9' 42" N., and of the second 

 70 26' 17" N. The number of vibrations in a mean solar day at 

 London being 86497'4, at Brassa they were 86530'507, and at Hare 

 Island SG562-6386 ; giving an acceleration of 33' 107 vibrations be- 

 tween London and Brassa, and of 32-1316 between Brassa and Hare 

 Island; or 65'2386 between London and Hare Island. 



Captain Sabine next proceeds to detail the preliminary experi- 

 ments relating to the pendulums, and the results of his various ob- 

 servations, made during the second voyage ; from which it appears 

 that at Melville Island in the Polar sea, in latitude 74 47' 12*4" N., 

 the mean diurnal acceleration amounted to 74'734 vibrations. From 

 the observations detailed at length in this paper, respecting the length 

 of the seconds' pendulum, at the several places of observation, it ap- 

 pears that its length at London being, as ascertained by Captain Ka- 

 ter, 39-13929 inches, at Brassait is 39*16929 inches ; at Hare Island 

 39-1984, and at Melville Island 39' 207 inches. This paper con- 

 cludes with a table, showing the diminution of gravity from the pole 

 to the equator, and the resulting ellipticity of the earth, deduced 

 from the preceding observations. The method followed in obtaining 

 these deductions is the same which is described by Captain Kater in 

 the Philosophical Transactions for 1819. 



