86 ANNUAL OF SCIENTIFIC DISCOVERY. 



table, while those which are shorter are taken by that part of the 

 rollers that is farther along. To avoid distributing the broom corn 

 throughout the whole length of the assorting rollers, portions of the 

 loAver roller are turned out, leaving only enough to constitute the axle, 

 and thus prcA'enting any of the material from being draA\ r n through in 

 these sections, which divides the assorted material into several series 

 or parcels, in number equal to that of the sections cut in the lower 

 roller. 



VENTILATION BY CHIMNEYS. 



AT the Royal Institution, in a series of lectures on chemistry applied 

 to domestic purposes, Dr. Faraday introduced various illustrations to 

 show the importance of the functions of the chimney. " A parlor 

 fire," he obserA T ed, "will consume, in twelve hours, forty pounds of 

 coal, the combustion rendering 42,000 gallons of air unfit to support 

 life. Not only is that amount of deleterious product carried away and 

 rendered innoxious by the chimney, but five times that quantity of 

 air is also carried off' by the draught, and ventilation thus effectually 

 maintained." The force of a draught Avas illustrated by a descending 

 flue. A colored flame was held near the end of a tube bent like an 

 inverted syphon. As soon as the tube was heated, the ascent of air 

 within the longer arm of the tube drew the flame downwards into the 

 shorter arm Avith considerable force. Since the ascent of smoke up the 

 chimney depends on the comparative lightness of the column of air 

 within to an equal column without, the longer the chimney the 

 stronger will be the draught, if the fire be sufficiently great to heat the 

 air ; but if the chimney be so long that the air is cooled as it 

 approaches the top, the draught is diminished. A case of this kind 

 occurred at a light-house on the Isle of Portland. The chimney which 

 ventilated the building and lantern Avas carried on the outside, and in 

 winter time the draught was so much impaired that the AvindoAvs 

 became dim and the light obscure. An attempt had previously been 

 made to remedy the defect by lengthening the chimney ; but that, of 

 course, had made it smoke all the more. The application of a jet of 

 steam to increase the blast of locomotive engine furnaces Avas illus- 

 trated. The lo\ver end of a bent glass tube Avas placed in a dish which 

 contained liquid, the upper end being inserted into a large and hori- 

 zontal tube. A jet of high-pressure steam directed through the larger 

 tube caused such a rush of air to supply the place of the air expelled 

 by the steam, that the colored liquor rose to the top of the tube. The 

 mechanical force of a jet of high-pressure steam Avas shown by causing 

 it to sustain an egg, which Avas seen dancing about in the air without 

 anything apparent to support it. 



SUBMARINE EXPLORER. 



A SUBMARINE vessel, of someAvhat noA'el construction, has been recently 

 built in New York, under the direction of a Mr. Alexander, a French- 

 man. It consists of a large iron shell, somewhat resembling an egg, 

 both ends, hoAveA r er, being of the same size and form. This shell is 



