236 Dr. Bence Jones on Ventilatioti, [April 18, 



In conclusion, it was stated that at present there were several 

 regenerative engines in constant practical operation, in this country 

 (at the works of Messrs. Newall and Co., at Gateshead), in France, 

 and in Germany, varying from five to forty horse power, which had 

 proved the practicability of the principle involved, although they 

 were still capable of improvement. Several other engines were now 

 in course of construction at establishments celebrated for precision 

 of execution, and with the advantage of Mr. Siemens' increased ex- 

 perience in designing them. He had been fortunate to meet with 

 men of intelligence and enterprise, lately joined together in a 

 public company, whose co-operation insured a more rapid deve- 

 lopement of his invention than individual effort could produce. 

 The benefit he had hoped to derive from his discourse, incom- 

 plete as it necessarily was, would be realized, if those men, 

 eminent in science, whom he saw around him, would accept his 

 labours as an earnest towards the practical realization of the dyna- 

 mical theory of heat, and hasten its triumphs by their own re- 

 searches. It was impossible to over-estimate the benefits that 

 mankind would derive from a motive force at one-third or one- 

 fourth part the cost and incumbrance of the present steam-engine. 

 The total consumption of coal would certainly not diminish ; but 

 our powers of locomotion and production would be increased to 

 an extent difficult to conceive, tending to relieve men from every 

 kind of bodily toil, and hasten the advent of the hoped for period 

 of general enlightenment and comfort. 



[C. W. S.] 



WEEKLY EVENING MEETING, 



Friday, April 18. 



Sir Benjamin Collins Brodie, Bart. D.C.L. F.R.S. Vice- 

 President, in the Chair. 



H. Bence Jones, M.D. F.R.S. M.R.I. 



PHYSICIAN TO ST. GEOKGE'S HOSPITAL. 



On Ventilation, and the means of determining its amount. 



In regard to all our wants, three questions constantly present them- 

 selves. First, what it is exactly that we do want ; secondly, when 

 have we got what we do want ; and thirdly, how to get what wc want. 



