462 EDITOR'S NOTES. 



solar day. These corrections, multiplied by 1*65, be- 

 come respectively 9 S *52 and 10 S *38 ; or the number of 

 vibrations in a mean solar day, computed from the 

 results with the invariable pendulum before Bessel's 

 discovery was made, required to be increased by 

 (9 s -52 - 5 8 -7o =) 3 s -77 at Sierra Leone, and (10 8 -38 



6 8 '27 = )4 S< 11 at Spitzbergen. But the acceleration 

 between these stations would only have to be corrected 

 for the difference between these numbers, i.e. for (4 s * 11 



3 s -77=) 8 *34 ; and as the whole acceleration be- 

 tween Sierra Leone and Spitzbergen is 214 S> 8 in a mean 

 solar day, an error of O s> 34, or about its -g-J-oth part, would 

 be of very small import. But it so happens that even 

 this small error is in great part compensated by a nearly 

 equivalent correction in an opposite sense, which is oc- 

 casioned in the reduction to a uniform temperature as a 

 consequence also of Bessel's discovery. The equivalent 

 in seconds to 1 of Fahr. was inferred to be 8 *421 in a 

 mean solar day, from experiments made in London 

 previously to 1828, in temperatures respectively 45-81 

 and 83-55 of Fahr. (Pend. Expts., pp. 202207.) In 

 this deduction the old and erroneous buoyancy formula 

 was employed; but, on a recomputation with the old 

 correction multiplied by 1*65, the true equivalent for 

 1 is found to be 8 -43. (Sabine, in Phil. Trans., 1829, 

 p. 238 ; and Airy, in Phil. Trans., 1856, p. 317.) Now 

 the temperature of the pendulum during the experi- 

 ments at Sierra Leone was 80%52, and at Spitzbergen 

 41*13, the difference being 39*39, which being multi- 

 plied by (0 8 -43-0 8 -421 =) OH)09 is 8 -36 ; by which 

 amount the originally computed acceleration between 



