488 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



No. 3 from two directions at the same time, thus obviating the 

 dead-points which occur when power is applied to a crank in one 

 ri2:ht line. The description of this novelty was received with a 

 round of applause. 



The chairman remarked : So much ingenuity has heretofore been 

 expended in gearing and motor connections that we seldom meet 

 wath anything new. The last invention of Dr. Rowell deserves 

 our commendation. The first was only a modification of that 

 found in the books, for, as will be seen by an illustration on the 

 black-board, by having three cranks on the same axis, motion may 

 be communicated to three similar cranks of another shaft at a dis- 

 tance by merely connecting the like parts by a rope or wire, 

 because the power can be constantly communicated by drawing, 

 and not by pushing, as will be necessary where only two connec- 

 tions are made. 



Mr. T. D. Stetson said this experiment was made on a large 

 scale at Niagara, where power was communicated by means of four 

 cranks to other four cranks, at a distance of two hundred and fifty 

 feet. It was found, however, that the sag and stretch of the wire- 

 ropes used in this instance, being of course expanded and con- 

 tracted by changes of temperature, were so great that the appa- 

 ratus proved a failure. For short distances such connections may 

 be eiBcient. 



Mr. L. B. Page said the beautiful arrangement of Dr. Rowell 



reminded him of a connection of a difierent kind used in the oil 



regions. He knew an instance where one steam engine of forty 



horse-power worked about twenty oil pumps, and the connections 



of timber producing a reciprocating but no rotary motion, were 



not less than a 7mle and a half long. He promised to present 



before the Association, at a future meeting, a drawing of that novel 



arrangement. 



Ventilation. 



This subject, selected for discussion, was first taken up by Dr. 

 Rowell, who averred that all drafts through doors, windows, ven- 

 tilators and chimneys, depended on the difierent degrees of rare- 

 faction of the air. The highest air ascends because it is displaced 

 by air of greater density. The whole action is, therefore, the 

 result of gravitation. In order to make this clearly understood, 

 he had prepared a little apparatus which could be copied by 

 young experimenters in natural philosophy. It consists of a glass 

 beaker, which i^ to be partly filled with water; a glass tube with 



