TRANSACTIONS OP THE SECTIONS. 109 



rollers, and moving forward about an inch per minute. The coals employed are 

 common siftings or screenings, heaped in a hopper (which may be made to hold 

 fuel for an unlimited time) outside the furnace door, which slides upwards. This 

 door is left a little open, and the small coal is spread uniformly over the bars 

 by passing under it. The air is constantly supplied through the bars, directly 

 to the fuel while burning ; and in this way perfect combustion is obtained. The 

 bars being slowly moved on, carry the ashes to the ash-pit, which lies at the 

 back of the grate. Clinkers are prevented from encrusting the bars by their passing 

 under a gauge, which effectually removes them ; and the burning away of the bars 

 is prevented by their constant motion from the hottest place. The bars or chains, 

 with their rollers and driving wheels, are fixed in a frame, which can be completely 

 drawn out from under the boiler for the purpose of removing injured bars, or any 

 other purpose. 



On an Indicator of Speed of Steam Vessels. By J. S. Russell, F.R.S.E. 



This was a simple application of a well-known principle ; it was not novel, but he 

 had applied it successfully, although others had failed. It depended on the hydro- 

 dynamical fact, that if a reservoir be filled with water to a certain height, the water 

 will flow from an orifice at the bottom with a velocity proportionate to the height ; 

 and conversely, if the reservoir be empty and this orifice turned towards a stream, 

 the water will rise in the reservoir to the height proportionate to the velocity. His 

 plan was to pass a tube through the bow of the vessel, and carry it along the floor- 

 ing to the centre of gravity of the vessel", where it terminated in a vertical glass 

 tube, exhibiting the weight of water within. To this tube there was attached a 

 moveable scale, the zero of which being placed on a level with the point at which 

 the water stood when the vessel was at rest, the rise of the water in the tube when 

 the vessel was set in motion exhibited the velocity at which the vessel was passing 

 through the water. He had tested the accuracy of this indicator by sailing vessels 

 at least twenty times, over a measured distance of 15f miles, and comparing his tube 

 with Massey's log, the common log, calculations from the number of strokes, &c, 

 he found it more accurate than any. By putting a stopcock in the pipe just under 

 the glass tube, he was enabled to regulate the orifice until the greatest regularity 

 was obtained, and he could now depend on the indications within the twentieth of a 

 mile. From these experiments he had constructed a scale, which he exhibited, and 

 of which the following is an extract ; the first column exhibiting the speed in miles 

 per hour, and the second the height of the water in the tube above the zero line, ex- 

 ' pressed in feet : — 



Miles per hour. Feet on the scale. 



On certain Plans for Ventilation recently adopted in Glasgow. 

 By Robert Chambers, F.R.S.E. 



The plans described in this paper were suggested by Mr. Joseph Fleming, sur- 

 geon, Anderston (a suburb of Glasgow). Mr. Fleming wrote a pamphlet on the 

 subject in 1833. The object of Mr. Chambers's paper was to give an account, illus- 

 trated by drawings, of the various modes in which Mr. Fleming's principle had been 

 applied since that period. 



The principle is that which has been so well exemplified in other quarters — fire- 

 draught. 



Mr. Chambers first described a large house connected with a mill in Anderston, 

 which usually contains about five hundred inhabitants of the humblest class, and 

 which used to be a constant focus of pestilential disease in consequence of the filthy 



