72 .REPORT—1858. 
ture for the jet, which would not be liable to be stopped up by the oily deposit from 
common coal-gas; this, however, was completely removed by making burners of ordi- 
nary pipeclay, piercing them with a fine needle, drying, and then making them red- 
hot in a common fire. 
The instrument in this state had been in constant use for seven or eight years, 
during which it had been chiefly employed to regulate a small apparatus for carrying 
on a series of experiments on incubation, and its steadiness of action had proved to be 
all that could be desired. The author mentioned to the Section as one proof of its 
utility in such investigations, that it had enabled him to prove clearly the evolution 
of vital heat in the process of hatching eggs, which are shown to acquire a tempera~ 
ture for some days before the completion of their incubation, several degrees above 
the atmosphere in which they are placed; a fact, which he believed had not been veri- 
fied by actual experiment, though it would naturally be anticipated. The author 
stated that the contrivance was the joint production of himself and Mr. $8. Smith of 
Halifax. 
GEOLOGY. 
Address by Witi1AmM Hopkins, M.A., F.R.S., President of the Section. 
Tuer President, in opening the Section, proceeded to observe :—the existence of 
mammalian life in its earlier stages on the surface of our planet, the conditions of its 
existence, and the period of its introduction, have always furnished questions of the 
highest philosophical as well as palzeontological interest. You will be aware that some 
geologists regard each new discovery of mammalian remains, in formations preceding 
the older tertiaries, as a fresh indication of the probable existence of mammalia in 
those earlier periods in which no positive proof of their existence has yet been obtained ; 
while others regard such discoveries only as leading us to an ultimate limit, which will 
hereafter define a period of the introduction of mammalia on the surface of the earth, 
long posterior to that of the first introduction of animal life. Be this as it may, every 
new discovery of the former existence of this highest class of animals must be a matter 
of great geological interest. An important discovery of this kind has recently been 
made, principally by the persevering exertions of Mr. Beckles, who has detected in 
the Purbeck beds a considerable number of the remains of small mammals. The 
whole of them are, I believe, in the hands of our President, Mr. Owen, for the deter- 
mination of their generic and specific characters ; but Dr. Falconer seems already to 
have recognized among them seven or eight distinct genera, some of them marsupial, 
and others probably placental, of the insectivorous order. I may also notice, as a 
matter of great palzontological interest, the recent discovery of a new ossiferous caye, 
near Brixham, in Devonshire, of which some account is to be brought before us during 
this meeting. The past year has been fruitful in paleontological researches, but it is 
not my purpose to notice them in detail. 
I proceed to one or two points of interest in the physical department of our science, 
The internal structure of rock masses, with reference to joints, planes of cleavage, and 
crystallization, is a subject of great interest to those who would study the operation 
of physical causes in producing all the modifications of state through which the matter 
now forming the outer crust of the globe must have passed in the lapse of geological 
time. A considerable number of observations have been made by different geologists 
respecting the positions of the planes of joints and of cleavage, but I confess myself 
little satisfied with any laws of the phenomena unless deduced from observations of 
far greater accuracy of detail than that by which these observations have generally 
been characterized. I allude more particularly to this subject, because some progress 
has, I think, been made in the mechanical explanation of a part of these phenomena, 
those which relate to the laminated cleavage structure. Direct experiments have 
been made by Mr. Sorby and Dr, Tyndall, which leave no doubt of the possibility of 
producing this structure by direct pressure alone; and in certain simple cases, in 
which the divisional planes form a system of parallel laminz, this mechanical cause 
may be sufficient to account for the phenomena. But in many other cases in which 
OO 
