140 



NATURE 



\7une 25, 1874 



rimetry, and the like. This room at present contains 

 an apparatus devised by Prof. Clerk Maxwell for deter- 

 mining the viscosity of air.* This is done by causing 

 three glass plates to vibrate between four parallel fixed 

 plates in an air-tight receiver, by means of the torsion of a 

 steel wire. A mirror being connected with the plates, the 

 amplitude of vibration is determined by viewing through 

 a telescope the image of a fixed graduated scale formed 

 by the mirror. The room G on the ground-floor is used 

 for unpacking apparatus, &c., which is brought directly 

 into this room from the street. The apparatus is then 

 raised to the floor above by means of a lift at /■. H 

 Fig. I is used for a workshop ; it is furnished with a car- 

 penter's bench and tools, two vices, c&c. A 5-inch self- 

 acting screw-cutting lathe will shortly be added, and 



Fig. t.— Ground Floor. 



thus the means will be provided for adjusting and 

 repairing on the premises most of the apparatus re- 

 quired in physical research. The room K is called the 

 battery room ; it is situated immediately under the 

 lecture-room, into which wires will be carried from the 

 battery through small hatches in the floor. The battery 

 which will be employed is Sir William Thomson's tray 

 battery, in which the zinc plates will be supported on 

 porcelain cubes of i-inch edge. The internal resistance 

 of one of these cells is about •16 ohm. A gas holder con- 

 taining oxygen gas will also be kept in this room, from 

 which pipes will be carried up into the lecture-room, so 

 that the oxy-coal-gas limelight will be always at hand. 

 The south wall of this room, which is 18 in. thick, passes 

 up into the lecture-room independently of the flcor, and 



* See the Bakerian Lecture, Phil. Tr.ins. i£66. 



carries the lecture table. The floor of the lecture-room is 

 supported on two brick piers, which are built about an 

 inch away from this wall. On the stone pavement of the 

 ground-floor a long line will be carefully measured, and 

 with this the other measures of length used in the labora- 

 tory will from time to time be compared. At f is an old 

 stone gateway of the sixteenth century, which formerly 

 served as the entrance to the Science Schools. 



Passing now to the east end of the first floor we find our- 

 selves in the general laboratory (L Fig. 2). This room is 

 60 ft. long and 30 ft. wide, and is designed to contain twelve 

 large tables, though there are but ten in it at present. 

 Each of the tables in this, as in all the rooms on the first 

 and second floors, issupported independently of the floor 

 on beams resting on brackets fixed in the walls of the 



rooms below, holes being left in the floor and blocks placed 

 upon the beams so as to be flush with the flooring ; it is 

 on these blocks that the legs of the table rest. A stand- 

 pipe, conveying gas, passes up through the centre of each 

 table, and carries connections for four 13unsen or other 

 burners, but can be removed at pleasure. A closet, 

 provided with a good draught into the chimney, will be 

 erected at the east end of this laboratory, in which any 

 experiment producing objectionable fumes, &c., can be 

 conducted. This laboratory is intended for the general 

 use of .students. Each room, with one or two exceptions, 

 is provided with an open hearth fcr a basket fire and a 

 ventilator leading into the chimney near the ceiling. 

 Water is also laid on to all the rooms, which are likewise 

 furnished with leaden sinks ; and a plentiful supply of 

 indiaiubber tubing lined with canvas will be always on 



