Eescarrh Lahoratory of tlie, Royal College of Physicians. 523 



be driven at any part of the room at 360 different speeds. 

 The northern end of the room is occupied by a large 

 cabinet, in which are stored the various pieces of apparatus. 

 Near the south end is a stone pillar bedded in the 

 ground, so arranged as not to be affected by movements in 

 the room. There being no thoroughfare in the lane, no dis- 

 turbance can arise from wheel traffic. Around the pillar is 

 lixed a table to which the galvanometer wires are attached. 

 The galvanometer is placed on the stone pillar in a glass case 

 with a hinged door, and is always kept ready for use, short 

 wnres beiniz carried from the table to the instrument. A 



Fig. 3. 

 (a) Drum ; (6) screw bearing-point ; {c) toothed wlieel ; {d) coarse 

 worm ; (e) finer Avorm : (/) driving pulley, 



hinged Uamp table, and brass rods over which curtains are 

 hung, complete the galvanometer fittings. Work tables 

 occupy the remainder of the centre of the room. 



The recording drum (Fig. ?») designed by Dr Milne Murray, 



