336 SECTION MECHANICS. 



The air is tainted with a thousand different effluvia, and however little 

 agreeable it may be to hear it spoken, this ill, which all the human 

 race is heir to, cannot be avoided. We may say of it, as the poet says 

 of death : 



" Le pauvre en sa cabane, ou le chaume le couvre 



Est sujet a ses lois 



Et la garde qui veille aux barrieres du Louvre 

 N'en defend pas les rois." 



Let us therefore unite our efforts to ward off these evils, and to 

 establish healthy dwellings for the poor as well as for the rich, in order 

 that all alike may enjoy these two great blessings : 

 " Mens sana in sano corpore." 



The PRESIDENT : I am sure we have all enjoyed the discourse 

 which General Morin has given us upon this very important subject of 

 ventilation. The time has now come when we have all experienced 

 the great advantage of ventilation, and have all come to the conclusion 

 that it is very desirable. But opinions differ very widely on the best 

 modes of carrying into effect under different circumstances. It is a 

 very difficult subject, which General Morin has followed up with great 

 care and perseverance and the results which he has brought before us, 

 are, I think, such as will commend themselves to our most earnest 

 attention. I beg now to pass a most hearty vote of thanks to him for 

 his communication. 



The vote of thanks having been passed, 



The PRESIDENT : I will now call on Messrs. E. Dent & Co. to give 

 us their communication 



ON TIME MEASURERS. 



Messrs. E. DENT Co. : A clock consists of two distinct parts a 

 pendulum oscillating in a certain small interval of time and a 

 mechanism whose duty it is to register the number of these oscillations 

 and to maintain them by giving to the pendulum periodically a little 

 push or impulse for without this it would soon come to rest. 



In order that a clock may perform accurately it will be at once seen 

 that the time occupied by each oscillation of the pendulum must be a 

 constant quantity. 



For this it is ncccssr.ry thnt its theoretical l^n^ili should be invariable; 



