NOTES AND QUEKIES. 
227 
sidered erroneous on the folio-wing grounds: — (1) he knows no section in 
Jamaica in which the relation of the TVhite Limestone to the Hippurite- 
limestone is seen ; (2) the White Limestone he believes to be of Miocene 
age ; and (3) the shalj and sandy beds represented in the section as over- 
lying the White Limestone he considers to be undoubtedly in infra-posi- 
tion. The author then discussed the question of the age of the White 
Limestone, first on physical grounds, and afterwards palaeontologically, in- 
ferring tliat it was decidedly of Miocene date ; and in conclusion he re- 
marked that the White Limestone had probably been deposited slowly in 
a tranquil sea, and discussed its relation to the Tertiary beds of the other 
West Indian Islands. 
4. "Facts and Observations connected with the Earthquake which oc- 
curred in England on the morning of the 6th of October, 1863." By 
Fort-Major T. Austin, F.G.S. — Earthquakes in the British Isles attract 
usually but little notice, owing probably to the mild form in which they 
generally occur ; but that one treated of in this paper, owing to its greater 
violence, aroused attention to the subject. The disturbance was said to 
extend from a point in St. George's Channel forty or fifty miles to the 
north-west of Pembrokeshire to Yorkshire, and the focus of the disturbance 
to be situated near the former spot. The author brought forward a num- 
ber of facts for the purpose of proving the intensity of the shock, the time 
at which it occurred, the number of vibrati(Uis, their direction (which was 
considered to be from W.N.W. to E.S.E.), and the occurrence of inci- 
dental phenomena, and concluded by passing in review the natural causes 
competent to produce these and other characteristics of earthquakes. 
NOTES AND QUERIES. 
The Meisubement of Heiohts by the Aneroid. — The following 
explanation of the use of the aneroid in taking heights is given by Mr. 
Spencer Browning, of the I\Iinories, in a pamphlet published by him. 
His aneroids, especially his mountain- and small pocket-instruments, are 
unequalled for finish and accuracy. 
The t/icort/ on which the measurement of lieights is effected by the 
barometer, the aneroid, or the sympiesometer, is exceedingly simple, though 
the application of the theory depends on formula; which have required 
mathematical skill to construct, and which include " constants " obtained 
by delicate experiment. 
Theory. — Let m and m} be two stations on a mountain side : required to 
find the difference of elevation between them. 
The aneroid (or barometer or sympiesometer) having been corrected for 
the effect of temperature upon Us own mechanism, shows at m the weight 
of a column of air, having the vacuum box of the instrument for its base, 
and reaching from m to the extreme limits of the atmosphere. Similarly, 
an observation at m' gives the weight of the upper portion of an identical 
column of air, reaching from m' to the limits of the atmosphere. 
Consec^uently the excess of pressure at m above that at m' gives the 
weight ot that part of the column which extends from the level of w to the 
level of m'. 
Knowing the weight of the column, if we also ascertain the specific 
gravity of the air that composes it, we have data for calculating its height. 
