yune 25, 1874J 



NATURE 



141 



hand in case of fire. The room marked M in Fig. 2 is 

 the Professor's private room. It communicates with the 

 general laboratory by two hatches, which can be opened 

 or closed at pleasure. In the south-west corner of this 

 room is placed Sir William Thomson's quadrant electro- 

 meter, made by White of Glasgow. N Fig. 2 is called the 

 apparatus-room. This room will be furnished with glass 

 cases and cabinets, in which will be kept the apparatus 

 which is not in immediate use, and amongst others several 

 classical instruments belonging to the British Association, 

 as for example the original standard unit of electrical 

 resistance and the governor, coil, &c., used in determining 

 this unit. The room O Fig. 2 is called the '■ preparation- 

 room ; " it communicates through a hatch with the lecture- 

 room P. It is intended that the preliminary arrangements 



Fic. 3— Third Floor. 



necessary for making experiments during the lectures 

 should be carried out in this room. The lecture-room P is 

 about 38 ft. by 35 ft. and 28 ft. high, and will afford accom- 

 modation for about 180 students. The lecture table, which 

 extends throughout the width of the room, is of oak, and 

 is supported on the top of an 18-inch wall as previously 

 described. The seats for the class rise at an angle of 

 about 30°, and there are three doors to provide sufficient 

 means of egress for the audience. The room is panelled 

 to a height of about 9 ft., above which the walls are brick 

 relieved by handsome pillars, which spring from triple 

 conical brackets, and support the ceiling. The room is 

 lighted by three windows at a height of about 17 ft. from 

 the floor, and one window below. Each window is fur- 

 nished with wooden shutters, which fold together, thus 



completely darkening the room. The shutters of the 

 three upper windows are opened and closed together by 

 means of endless screws attached to a horizontal shaft 

 which runs under each. The ceiling of the room consists 

 of wooden panels, those near the walls being perforated 

 and forming the bottoms of two horizontal shafts, which 

 lead into a chimney, thus providing an eiBcient means of 

 ventilation. Three of the panels over the lecture table, 

 as well as the styles between them, can be removed. 

 Above these are two strong tic-beams of the roof, from 

 which Foucault's pendulum or other heavy bodies may be 

 suspended over the lecture table. The panels and styles 

 adjoining the north wall of the lecture-room can also be 

 removed to allow of diagrams being suspended against 

 the wall. On the other three sides of the room the ceil- 

 ing- does not abut directly upon the wall but is coved in 

 the form of a quadrant of a circle, giving the room a very 

 beautiful appearance. This lecture-room is in every 

 respect a model room cf its kind. All the rooms on the 

 ground-floor and first floor, with the exception of the 

 lecture-room, are about 15 ft. in height. 



On the third floor the room O Fig. 3 is intended for 

 experiments on acoustics. The room R will be employed 

 for making drawings and calculations ; S will be devoted 

 to researches on radiant heat; and Tand U are for optical 

 experiments. V is the electrical room. The air in this room 

 will be kept dry by Mr. Latimer Clark's contrivance, which 

 consists of a heated copper roller over which an endless band 

 of flannel passes. The roller is heated by gas-lights within 

 it, and, being kept in constant rotation, every part of the 

 flannel becomes heated in turn by passing over it. The 

 vapour which rises from the heated flannel is carried off 

 by the current of air which supplies the burners inside the 

 roller, and escapes by the flue. The flannel when thus 

 dried .and cooled passes into the open air of the room, 

 where it again absorbs moisture from the air, which thus 

 becomes dried, so that the electrical instruments in the 

 room are preserved in a highly insulating condition. 

 From this room a small doorway enters the lecture-room 

 at a height of about \y ft. from the floor of the latter. An 

 insulated wire connected with the prime conductor of the 

 electric machine will pass through this doorway and thus 

 supply electricity on the lecture table when the air in the 

 lecture-room is too damp to allow of the satisfactory work- 

 ing of the machine. \V is a small dark room for pboto- 

 giaphic and other similar purposes. A small window for 

 a heliostat is placed in the west wall of the electrical room, 

 opposite the door, from which a beam of light may be sent 

 along the whole length of the building so as to allow of 

 diffraction and other experiments, with rays of light 

 120 ft. in length. All the rooms are heated by hot-water 

 pipes connected with a boiler in the basement. Near the 

 east end of the building copper pipes are employed on 

 each floor for the sake of the magnets in room B. 



A lofty flight of steps in the tower leads from the second 

 floor into the roof above the lecture-room, and a few more 

 steps lead into the highest room in the building, which 

 occupies the upper portion of the tower, its floor being 

 more than 50 ft. above the ground. In this room will be 

 placed a Bunsen's water pump, the water from which will 

 thus have a vertical fall of considerably more than 50 ft. 

 This pump will be used to exhaust a large receiver, from 

 which pipes will communicate with the different rooms. 



