EXPERIMENT STATION BULLETINS. 



191 



Machine. 



Evans „. 

 Hippard 

 ScoUay-. 



Number of 

 Revolutions. 



H 



18 



7 



Power — Pounds, 



20 

 11 



28 



Foot-pounds. 



880 

 792 



784 



Time— Seconds. 



4 



5 

 20 



In the above table the power given is that required for raising the sash 

 when applied to the periphery of a wheel 15 inches in diameter. 



This is the size of the wheel furnished with the Hippard machine, but 

 that on the Evans machine is 16^ inches in diameter. If we take the average 

 power that must be applied to the periphery of this wheel, which is 18 

 pounds, and multiply it by 11, the number of required revolutions, we have 

 198, which is the same as will be obtained if 11 pounds, the power required 

 by the Hippard machine, is multiplied by 18, the number of revolutions it 

 requires. It will thus be seen that taking the machines as manufactured, 

 they are equally efficient. The Evans machine requires fewer revolutions, 

 but greater power to raise the sashes, than is needed to raise them to the 

 same height by the Hippard machine. 



Either of these machines will give satisfaction. We have shown them 

 to a large number of persons, whose preferences seem to be about equally 

 divided between them. 



The Scollay machine only requires seven revolutions of the wheel to 

 open the sash, but from the method of applying the power it takes four or 

 five times as long to open the sash as with either of the other machines. 

 The power being applied directly to the shaft, it is considerably greater 

 than with either of the other machines. It is a substantial and simple 

 machine, costing about the same as either of the others. From the method 

 of attachment, as stated above, it takes considerably longer and the expend- 

 iture of much more muscular force to raise the sash with this machine than 

 with the other. We have seen machines similar to the Scollay with crank 

 and gearing attachments that worked very easily. 



STEAM VERSUS HOT WATER FOR HEATING. 



The two houses being constructed exactly alike, it afforded an excellent 

 opportunity for making a comparative test of the merits of hot water and 

 steam, for the heating of small greenhouses, and the heating plants were 

 arranged for this purj^ose. 



We decided to use small wrought iron pipes in the hot-water-heated 

 house in preference to the four-inch cast iron pipes that have been almost 

 universally used until within the last few years. 



The cost of the pipe would be only about half as much as for the four- 

 inch; it screwed together in long lengths instead of being packed every 

 nine feet or less; and furthermore we believed it would prove more 

 economical. 



