136 



TRANSACTIONS OF THE 



for instance, be closed at ten o'clock at night, and the heat, instead of being thrown 

 back into the furnace, is allowed to pass through the lateral tube into the ventila- 

 ting flue, and so continue until six the next morning, the interior of the flue will 

 become well heated, so that the next day, when the current of warm air is 

 restored to the parlor, the heated sides of the ventilating flue will continue to rarify 

 the air within them for many hours afterwards, thus causing an upward draught. 

 There being no danger of a regurgitation of the air of the flue through the venti- 

 lating register (as is the case when ventilating openings are made in ordinary flues), 

 connections with the apartment to be ventilated may be made at any point, and 

 even carried to the opposite side of the house, between the beams, to ventilate 

 distant apartments. A great advantage of this plan is the capability of having a 

 large number of ventilating flues put in connection with the furnace. In fact, the 

 number may correspond with the number of hot-air registers, and thus any desi- 

 rable amount and extent of ventilation be obtained. Ventilating openings may be 

 made either at the floor or ceiling, or both, and all openings should be commanded 

 by a register. The ventilating flues should be gradually enlarged in area, as they 

 ascend, but care must be taken not to enlarge them too mnch. This arrangement 

 may be introduced into many houses already erected, by connecting the hot-air 

 tubes with such of the ordinary chimney flues as are not used with fire, but they 

 will not, of course, operate so efficiently as flues built for the purpose, as directed- 



{^Large silver medal awarded. 



Palmer^s 

 Patent Artificial Leg. 



Palmer & Co., 378 Broad- 

 way, N. Y. 

 The articulations of knee, 



ankle, dnd toes, consist of de- 

 tached ball-and-socket joints 



ABC. The knee and ankle 



are articulated by means of 



the steel bolts E E, combin- 

 ing with pZafes of steel firmly 



riveted to the sides of the leg 



D D. To these side plates 



are immovably fastened the 



steel bolts E E. The bolt* 



take bearings in solid wood 



(properly bushed) across the 



entire diameter of the knee 



and ankle, being fourfold 



more reliable and durable 



than those of any other con- 

 struction. Allthe joints are 



so constructed, that no two 



pieces of metal move against 



each other in any part of the 



limb. The contact of all 



broad surfaces is avoided 



where motion is required, 



and thus friction is reduced 



to the lowest degree possible. 



internal view. 



External view. 



