PROCEEDINGS OF SECTION H. 357 
The lecture-room will be provided with a fixed blackboard 
of ample horizontal dimensions. The popular shifting black- 
board, about 4 ft. square, resting on a shaky easel, has long 
been the writer’s pet aversion. A proper blackboard should 
be made of slate or cement on a solid wall, and should be at 
least 12 ft. long. A large extent of vertical dimension is of 
little use, as practically one can work conveniently between 
levels little more than 2 ft. apart. Above the backboard will 
come arrangements for supporting and displaying diagrams, 
or, if necessary, a screen for lantern demonstrations. It is 
not proposed to have any fixed furniture in the room. A good 
substantial table, bequeathed to the writer by the late Pro- 
fessor Wilson, the founder of the school, will act as lecturer’s 
table, while the small movable tables and chairs, of which the 
University possesses some hundreds for examination purposes, 
will answer perfectly well for the students, at any rate for 
some years to come. At one side of the room near the lecturer 
will be a water tap, sink, and drain, the utility of which is 
obvious for many purposes, including motive power for ex- 
perimental apparatus. At each side of the blackboard is a 
door, one leading to an apparatus-room, the other to the pro- 
fessor’s study—a convenient room, 20 ft. x 16 ft., with a 
south light and plenty of wall space for bookshelves. 
The students reach the lecture-room from the main hall, and 
the professor has a separate entrance to his private room also 
from the hall. Behind these apartments comes the tower, 
which serves a number of purposes. 
1. The lower part of the tower provides space for the main 
staircase Jeading to the surveying and drawing department on 
the first floor, and also to a staircase leading down to the base- 
ment, where the standard of length is placed. 
2. It provides for a mercury column for testing pressure 
gauges. The height of the tower is sufficient to give a mercury 
pressure of 25 atmospheres, or nearly 400 lbs. per square in. 
3. It provides for the erection of an experimental set of 
sanitary fittings, with glass windows, to show siphonage ventila- 
tion, &e. Such an appliance is to be found in some of the 
best American schools. 
4. It carries at the top a tank containing over 2000 gallons 
of water. This will supply a constant reliable pressure tnrough- 
out the building, and to the hydraulic laboratory to be here- 
after described. 
5). It provides for experiments on the elastic properties of 
long wires, and other experiments requiring a clear, but acces- 
sible vertical space of considerable extent. 
6. It provides for illustrating operations in underground 
surveying, such as the transference of an azimuth from the 
top to the bottom of a shaft. 
