Marcu 25, 1897 | 
beads of glass of known mean specific gravity), which 
float in the liquid, and mark by their change of position 
the advance within the liquid of a stratum of given den- 
sity. Thus the state of the liquids can be seen at a 
glance without either disturbing the apparatus, or setting 
up more or less troublesome observing instruments. 
The picture shows the lecture-table with apparatus for 
illustrating gyrostatic action and precessional motion. 
On the table and to the right are ordinary gyrostats, to- 
wards the left are two hollow spheroidal gyrostats which 
can be filled with water, and between stands a model, 
well known to all Glasgow students, for illustrating the 
precessional motion of the earth, which arises from its 
gyrostatic action. One of the hollow spheroids is oblate, 
the other is prolate, with the same deviation from spher- 
icity in each case. When they are filled with water and 
rotated, the oblate spheroid behaves like an ordinary 
solid gyrostat ; the motion of the other is unstable, and 
NEA LORE 
489 
struments of more modern design, which are far more 
historically interesting. One of these is the first reflect- 
ing galvanometer used by Lord Kelvin as a receiving 
instrument for signals through a submarine cable, the 
identical galvanometer, in fact, with which signals were 
received on board ship in the famous cable expedition of 
1857, 1858 ; another is one of the pieces of apparatus 
with which Joule determined the dynamical equivalent of 
heat ; and another is a replica of Dr. Andrews’ apparatus 
for the investigation of the critical states of gases. 
In another room upstairs there used to be a complete 
museum of electrometers and other electrical instru- 
ments. There were to be found old attracted disc-, 
heterostatic, and idiostatic-electrometers, and a series of 
instruments illustrating the development of the quadrant 
form of electrometer, from the first rude model to the 
marvellously complete and delicate contrivance for 
measuring differences of electric potential, which is not 
Fic. 3.—Lecture Table, 
the spin disappears immediately. On the wall are dia- 
grams showing the construction of a gyrostat and its 
rotational stability under various modes of support which 
render it essentially unstable when there is no rotation. 
Above the lecture-table is a large opening extending to 
the roof, so that itis possible to suspend from the roof- 
beams pendulums, ropes, gyrostats, and many other 
things of great importance for physical illustration. 
The apparatus-room is a large apartment, like the 
other rooms of the laboratory, from eighteen to twenty 
feet in height. It contains two large cases of instruments 
occupying a large part of the floor-space, and two smaller 
wall-cases at the ends of the room. Here are stored the 
instruments used for class illustrations and research ; but 
in the cases also are many pieces of apparatus, quaint 
and old-fashioned in form and ornamentation, made 
to a great extent from fine old mahogany. Besides 
“urvater Hausrath” the cases contain several in- 
NO. 1430, VOL. 55 | 
these 
with gyrostats, precessional globe, &c., 
Field, Glasgow. 
(From a photograph by J. Loc khart 
and diagrams illustrating gyrostatic action. 
one of the least of the benefits Lord Kelvin has conferred 
on electrical science. 
Beyond the lecture-room, on the side remote from the 
apparatus-room, is the private room of the Professor of 
Natural Philosophy. There Lord Kelvin, in the early 
years of the new University buildings, used to work a 
good deal. Now the private room is occupied for the 
most part by his nephew, Dr. J. T, Bottomley, who has 
had the adjoining room fitted with benches, mercury air- 
pumps, and other apparatus suitable for investigation of 
the properties of high vacua. 
On the floor above the apparatus-room and lecture- 
room are further cases for apparatus, and a battery-room 
the floor of which is caulked to prevent liquid from pass- 
ing through into the rooms beneath. 
The Physical Department and Lord Kelvin’s house 
at the University are lighted with electricity. Current is 
generated for this purpose by a dynamo driven by a 
