54 H. J. Grayson : 



Oil the completion of the machine, it was not found possible for 

 some considerable time to house and use it under conditions favour- 

 able to a satisfactory trial of its capabilities. Hence perforce it 

 remained in an ordinary dwelling-house situated not far from a 

 railway, but otherwise fairly free from serious disturbing influ- 

 ences, other than those inseparable from such a location. 



Seeing that for a time no other alternative offered, it was^ 

 decided to make the best of the available accommodation. The 

 machine was set up on a brick pier, erected below the floor of a 

 small room used as a study, etc., in which the temperature condi- 

 tions were fairly even. In the main, the results from a series of 

 trials justified the experiment. Certainly, defects of various kinds 

 Were apparent, and for some of these remedies were devised, this 

 being one of the objects for which the trial was undertaken. But 

 the principal result of the experiment served to prove that it was 

 possible, in the intervals between the somewhat extreme fluctuations 

 of temperature to which our summer climate is liable, to rule fair 

 gratings, even under adverse conditions. 



Subsequently a large sub-basement room., having very thick outer 

 walls, situated under the main Library of the University, and suffi- 

 ciently remote from disturbing influences akin to those named, 

 was partitioned off into two smaller rooms. One of these is used 

 for spectroscopic examination and work, while within the adjacent 

 room a still smaller room has been constructed especially for the 

 accommodation of the ruling machine. The latter room has double 

 walls, the intervening space being filled with non-conducting 

 material, consequently a very uniform temperature can be main- 

 tained for a considerable period, the variations being mainly of a 

 seasonal character. Within this small room, a foundation of dry 

 sand, enclosed within cemented brickwork, has been laid down below 

 the floor level. A heavy stone slab, resting upon the sand, serves 

 to support a brick pier capped with a thick slate bench insulated 

 from the brickwork with rubber pads. The upper surface of the 

 slate is ground smooth and true, and carries the machine and 

 driving gear, other than the engine; the whole being enclosed within 

 a carefully constructed case, consisting niainly of heavy glass 

 sashes, affording ready access to every part of the apparatus. The 

 driving motor is placed outside the machine house, and does not 

 affect its temperature. As the gas consumption of the motor is 

 under one cubic foot per hour, any heat from this source is easily 

 conveyed from the room. 



