17- 



SCIENTIFIC NEAVS. 



[Feb. 24, iS 



in consequence of a portion of the gaseous constituents 

 not being able to attain the temperature necessary to 

 produce flame. Owing to this, nearly all the apparatus 

 made for heating water by gas are unsatisfactory, and 

 although the practical difficulties are known, it is by no 

 means easy to find a remedy for them. In June, 1886, 

 Mr. T. Fletcher discussed this subject in a paper he read 

 at the Gas Institute, and he illustrated it with some 

 interesting experiments. He showed that if water be 

 placed in a vessel which has a perfectly flat bottom, and 

 if this be heated over an atmospheric burner, there will be 

 a clear space of about one-fortieth of an inch intervening 

 between the top of the flame and the bottom of the 

 vessel. His contention was that for the reason mentioned 

 above, there was no actual flame contact, and in proof 

 of this he showed that if a piece of paper were pasted 

 on the bottom of the vessel it would not be charred 

 or even discoloured by the gas flame playing on 

 it. Seeing that paper is charred at a temperature of 

 about 400° F., he argued that the gases which came in 

 contact with the label on the bottom of the vessel were 

 at a lower temperature than 400° F., and that, therefore, 

 a large proportion of the heat which might be produced 

 by combustion of the gas was lost. To meet this 

 difficulty he fastened a considerable number of copper 

 rods or studs to the bottom of the vessel, allowing the 

 lower ends on the outside to be surrounded by flame 

 and the upper ends inside the vessel to be covered with 

 water. With this apparatus, Mr. Fletcher certainly 

 heated a given quantity of water much more quickly, and 

 thus reduced the consumption of gas. Since then he has 

 improved the details of construction, and in the accom- 

 panying illustration we show a very efficient circulating 

 boiler made on the principle above described. Various 

 sizes are made, the smallest being only six inches in 

 diameter and five inches high, and capable of heating 

 forty feet run of pipe two inches diameter. The larger 

 sizes will heat 60 and 120 feet run, respectively, of 2- 

 inch pipe. As regards the consumption of gas the 

 approximate allowance is one cubic foot for every 5 feet 

 length of pipe 2 inches diameter, to maintain the 

 temperature of the pipes at about 80° F. above that 

 of the surrounding air. 



We do not agree with Mr. "Fletcher in hisUheory as to 

 the paper label not being charred because there is [no 

 flame contact. It is probably true that there is no actual 

 flame contact with the bottom of the flat vessel, but there 

 is undoubtedly a high temperature very close to the 

 bottom, more than enough to char the paper were it not 

 in close contact with the copper vessel containing water. 

 Water cannot exist in a liquid state at a higher temperature 

 than 212° F., and it is the presence'of this fluid in a metal 

 vessel of high conducting power that alone prevents the 

 charring of the label. Our readers will probably remember 

 that in a previous number * we described a simple experi- 

 ment for illustrating the conduction of heat, and we have 

 merely to apply the same principle to the case of the 

 boiler. 



Without doubt the addition of the copper rods is an im- 

 portant step in the right direction, not only because there 

 is a large increase in the heating surface within and 

 without the boiler, but also because the ends of the 

 rods furthest from the bottom of the boiler are less 

 affected by the coohng influence of the water and can 

 consequently become hotter, and so in turn have less 



*Vol. I., page 33. 



coohng effect on the flame. Not only does this insure 

 more complete combustion of the gas, but the heating 

 effect is quicker, and with so small an apparatus as that 

 illustrated the results obtained are somewhat remark- 

 able. 



AUTOMATIC INTERMITTENT 

 SYPHON. 



A/T DELAVALLADE has invented a syphon which is 

 ■'■'-'•. capable of coming into action and stopping again, 

 automatically, without any supervision or interference. 

 We borrow the figures showing its construction from 

 our contemporary, La Nature. Fig. 3 gives a repre- 

 sentation of the entire apparatus as adapted to the 

 outlet of a water reservoir. Whatever may be the 

 irregularity of the water supply, the syphon will never 

 act as an overflow, and it will start itself as soon as the 

 desired level of the liquid in the tank is reached. When 

 the tank is emptied, the syphon stops and starts again 

 automatically a few hours later. The time of stopping, 

 and, in consequence, the height of water remaining in 

 the tank, are entirely under control. It is merely 

 necessary to perforate the short leg of the syphon with 

 a series of holes (a, fig 3), which are closed with wooden 

 plugs, or opened, according to the level of water require(J 

 in the tank. 



The apparatus is constructed in two different forms, as 

 shown in figs, i and 2. The principle of both is the 

 same. 



The bell-syphon (fig. 1) has an interior tube which 

 is fixed in the outlet-hole, and which has at its upper end 

 a circular tank of water, A. A movable bell, fitted with 

 a circular partition B, covers the whole and rests upon 

 the tube. This bell is furnished with two small external 

 tanks R R' connected by a tube (/) : the lower one (R) 

 communicating with the interior of the bell by means of 

 small holes. 



Two bent tubes (T T' ) put the tank R in communi- 

 cation with the two chambers (a, /3) formed in the bell 

 by the paitition B. A third tube, S, issues from R, 

 passes through the bell, and hangs vertically in the in- 

 terior of the central tube fixed in the outlet-hole. 



Fig. 2 represents the second form of the apparatus. 

 It is an ordinary syphon with two turns, the other 

 parts being similar to those just described. The part A 

 of the curved syphon will always remain full of water 

 like the tank A in the bell-syphon. 



When the tank is empty, the syphon will be entirely 

 without water except the part A. As the water rises 

 gradually in the tank, so it also rises in the short leg of 

 the syphon, in the tank R, by means of R', and in the 

 three tubes T T' S. Again, as the water rises, the air is 

 driven before it until the syphon commences to over- 

 flow. 



A certain amount of pressure then exists in the cham- 

 ber a ; in the chamber /3, on the contrary, the normal 

 atmospheric pressure is maintained, since the long leg of 

 the syphon is open to the air. From this instant the 

 action of an ordinary syphon 'may be produced if we 

 have the requisite conditions of flow, the air confined in 

 the upper parts of the apparatus being swept away by 

 the first rush of liquid. 



Let us suppose that these conditions are not fulfilled. 

 Air will then remain at the top of the syphon or of the 

 bell and tubes T T', and it must either be removed or 



