CHAPTER VIII 



GENERAL PRELIMINARY PREPARATIONS 



Vibration and its Prevention. Apart from the acquisition of 

 suitable apparatus, due consideration should be given to other 

 points affecting the final results. Possibly the chief among 

 these is the situation of the room or apartment in which the 

 work is to be carried out. It has already been mentioned how 

 greatly vibration of the apparatus is to be feared, especially 

 when taking photographs with high powers or of a highly 

 critical nature. It is obvious that such work is much influ- 

 enced by the situation of the apartment in which the apparatus 

 is fixed. Assuming that the work is being performed in an 

 ordinary house, the best position for the room is either in the 

 basement, or preferably a sub-basement or underground cellar 

 if such exists. This should have, if possible, either a concrete 

 or similar substantially built floor. At the Lister Institute of 

 Preventive Medicine, to carry the instrument designed by the 

 writer, which has already been described, two brick columns 

 were carried down for about fifteen feet below the floor-level of 

 the basement, and these again rested on a solid bed of concrete. 

 While it is not contended that such is by any means essential, 

 yet it will give an idea of how carefully such points must be 

 attended to, when a building or portion of a building is being 

 designed and erected particularly for this work. An additional 

 advantage of having a basement apartment is that it is usually 

 far less subject to rapid changes and fluctuations of temperature 

 than is a room situated farther up or at the top of the house. 

 In the latter the change of temperature even between night and 

 day at any time of the year is considerable, but in the former 

 situation it will be found that the range is small even between 



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