356 Scientific Intelligence. — Astronomy. , 
notion, when examined, appears to be no better supported than 
the commonly received one, that the brightest stars are nearest 
to us. — Dublin Philosophical Journal. 
2. Opposite Effects of a Change of Density of the Air , as 
effecting the going of a Clock. — Davies Gilbert, Esq. M. P. a 
short time ago published some ingenious investigations on the 
vibration of pendulums, and shewed, that on a change of an 
inch in the height of the barometer, an astronomical clock ought 
to change its rate, in consequence of the alteration in the buoyan- 
cy of the air, by two-tenths of a second a-day. Having applied 
to Mr Pond and Dr Brinkley to examine this point, he was 
surprised to find that they had discovered no such change. On 
reconsidering the subject, he finds a cause which before he had 
supposed too small to have any effect, almost exactly counter- 
acting the effect of the change of buoyancy. This cause is the 
alteration of the arc by the altered resistance of the air. He 
remarks : “ It is an extremely curious circumstance, that, with- 
out any reference to the attainment of this balance between op- 
posite disturbing causes, our best clocks should have been for- 
tuitously made to vibrate very nearly in the arc which reduces 
them to equality.” For the mathematical investigations and 
tables illustrative of this singular coincidence, we must refer to 
the Quarterly Journal of Science for October. — Dublin Philoso- 
phical Journal. 
3. Local Attractions. — The Connaissance des Temps 1827, 
contains an account of geodetical operations in Italy by the 
French geographical engineers, remarkable for the discordance 
it exhibits between results deduced from these operations, and 
from astronomical observations. Of the exactness of the Survey 
no doubt can be entertained from the recital given, and the as- 
tronomical results are founded on the observations of several 
most able astronomers. The discordances, which in one case 
amount to nearly 27", and in another to 17", are attributed to 
local deviations of the plumb-line, caused by irregular attrac- 
tion. The matter near the surface at Milan appears to attract 
the plumb-line considerably to the north of the vertical, and 
that near Bernini considerably to the south. — Dublin Philosophi- 
cal Journal. 
