CHAPTER IV. 



H Great Invention. 



" Since at contrivements we are skilful both, 

 For dexterous sleights, 'mongst mortals thine 's the prize." 



Homer. 



THIS ventilator was originally a revolving one, but finding 

 from experience that any ventilator having a mechanical 

 movement was liable to get out of order, and prove to be a 

 nuisance rather than a boon, this form was quickly and 

 wisely discarded in favour of the fixed ventilator, which, 

 since its introduction, has effected the almost complete 

 rejection by architects and experts of revolving and other 

 forms of mechanical ventilators. To test the comparative 

 merits of the fixed and revolving ventilator, a series of 

 experiments were conducted in Glasgow under the inspec- 

 tion of Sir William Thomson, the eminent electrician, and 

 a large and distinguished body of scientists, including 

 professors from several of the principal colleges in the 

 kingdom, architects, engineers, and medical men, when the 

 superiority of the fixed ventilator was fully demonstrated. 



Sir William Thomson, after further experiments with the 

 Air-Pump Ventilator, and prolonged observation of its 



