THE ;< SILENT SYSTEM. 103 



ventilation adapted to the peculiar requirements of prisons. 

 This system is called the " silent " system of ventilation 

 for prisons, being devised to meet the necessity of isolating 

 the cells from each other, and yet providing a continuous 

 change of air. The advantage of this system is that every 

 cell is separately and equally ventilated, perfect isolation 

 being at the same time secured ; for no sound can possibly 

 be conveyed from one cell into another through the venti- 

 lating openings, though as many as from ten to twenty cells 

 are ventilated with the one pipe, and three or four of these 

 lead into one upcast shaft, there also being no valves what- 

 ever used. 



Notwithstanding the complete success of the Air Pump 

 Ventilator, the innate restlessness of inventive genius has 

 led Mr. Boyle to discover an improvement, which he has 

 recently patented, and which is said to surpass the present 

 ventilator both in efficiency and simplicity. The improved 

 form of ventilator will, we understand, entirely supersede 

 that hitherto supplied, as it is not considered desirable to 

 submit to the public apparatus of this kind, however 

 efficient, while better results are attainable. In the 

 course of time it is very probable that even the new 

 and improved form will in its turn be superseded, for 

 Mr. Boyle refuses to sit down with self-satisfied triumph. 

 Onward, ever onwnrd, searching for the |>erfect, adding 



