250 



ERICSSON'S ENGINE. 



[1853 



the outlet and inlet valves are at the top of the cj'linder. c' is an 

 inlet, and c" an outlet valve. The air receivers of the four double 

 cylindei-s communicate with each other by connectino- pipes, and 

 thus form, in connection wilh tbe several comnnmicatiug pipes, 

 one common receiver, of so large a size, that as it is asserted, the 

 the elastic force of the compressed air )'eraains veiy nearly the 

 same in the working of tbe engine. The receiver is provided 

 with a guage. The communications between the I'eceiver and 

 the heater, and between tbe heater and the external air are closed 

 by two puppet-\alves. These vah-cs are shown in tlie diagram 

 at (7 and h. The one I will call the vpper and tbe other the 

 lower \-alve. Tbe thermo;neters at I, m, n, serve to indicate the 

 tempeiature of the entering and escaping air. When the working 

 piston reaches its lowest point, that is, is nearly in contact with the 

 cylinder bottom, the upper vah'e is opened by the machine, the 

 compressed air rushes from the i'eceiver through the regenerator 

 into the space underneath the working piston, and the piston is 

 forced up. At two-thirds of the stroke this valve is closed and the 

 heated air actsexpansively to tbe end of the stroke. The lower valve 

 is now opened, and the same body of air esca[)es through it into 

 the vertical pipe ?', which communicates with the external air; 

 passing again through the regenerator on its exit. 



Tbe Regenerator is an admirable contrivance of Captain Erics- 

 sou's for abstracting the heat, or the greater portion of it, from 

 the escaping air, and restoring it again to an ecpial body of air 

 enteiing the cylinder, to repeat the work performed by the air 

 which has just escaped; that is, for employing the same amount 

 of heat o\-er and over again. The regenerator consists 

 of a large number of disks of wire-netting, placed side by side 

 and in a vertical position, in a marginal frame by which they 

 are held very nearly in contact with each other, (seethe diagram) 

 Each disk is six feet high and four feet broad, tl e wire of which 

 it is made is ,', th of an inch in diamtcr, and there are tens of 

 thousands of minute meshes in the whole extent of the disk. 

 Tbe number of mesh&s in all the disks, added to the equal num- 

 ber of interstitial spaces between the disks, makeup, it stated, 

 over 20 millions of minute cells through which the air j^asses and 

 repas-ses, on its way to and from the working cylinder. In tliis 

 way it is brought into contact with several tbousand square feet 



of metallic suiface, and parts with or imbibes lieat almost instan- 

 taneously. It is stated that Captain Ei-icsson estimates the time 

 occupied by a particular particle of air in traversing the regCBerator 

 at about 3-ath of 3 second, and that this small interval of time 

 suffices for the transfer of some 400 ° of heat from the escaping 

 air to the wire, or from the wire to the entering cold air. The 

 clear opening for the passage of the air through the regenerator 

 is about twehe s<]^uare feet. 



We are told that the escape or waste air deposits all its heat, 

 with the exception of about 30 ° , in tbe regenerator, the tbermo- 

 raeter at m never standing more than 30 ° higher than that 

 at /. Ericsson estimates that in the case of the stationary engine 

 the amount of fuel wasted in process of transfer, was only two 

 ounces of coal per hour per horse-power, while the amount wasted 

 by the radiation of the heated parts was about nine ounces per hour 

 per horse-power, and the entire consumption about 11 ounces. 

 But it should be observed that his calc\ilation involves the sup- 

 posilion that the estimated horse-power (CO) was realized in the 

 actual working of the engine. We shall be better able to judge 

 of the probability of this, after we have considered the details of 

 the performance of the engines of the Ericsson. 



After the engine has got into full operation, and the regene- 

 rator has reached its normal condition, there is a great dift'erence 

 between the temperatures of the inner and outer surfaces of 

 the regenerator. We are told that in the case of the I'cgenerator 

 of the stationary engines this difference was never less than 

 350 ° . The exjilanation is found in the fact that the heated air 

 on its escape through the regenerator, must undergo a continual 

 diminution of temperature, as it parts with its heat to the suc- 

 cessive wire-netting, and on the other hand the entering cold air, 

 on passing through the successive disks, which are of a higher 

 and higher temperatui'e, will tend to lower the temjierature of 

 each one of these disks, and at the same time to increase the 

 difference of the temperature between the outer and inner sur- 

 faces of the regenerator, and thus to compensate for the tendency 

 to equilibrium of temperature produced by the flow of heat from 

 the inner towards the cooler outer suiface. For, while it will 

 reduce the temperature of the outer surface, if the regenerator 

 has sufficient thickness, nearly to an equality with the temperature 



