TRANSACTIONS OF THE SECTIONS. 
159 
On Unchanged Steam. By Mr. Piiosser. 
The author explained and commented or. the plan adopted in the ‘Arctic’ steam- 
packet, of giving additional heat to the steam on its passage to the cylinders by 
nposing it more directly to the action of heat. 
& Means of realising the advantages of the Air - Engine. By W i r.LI A M 
John Macquobn Rankine. Civil Engineer, F.R.SS. Land, Edin. SfC. 
Ilia paper consists of four sections. In the first are explained the two funda¬ 
mental laws of the mechanical action of heat, and their application to determine the 
®aency of theoretically perfect engines, working between given limits of tempera¬ 
te; and it is shown that, as the efficiency increases with the distance between 
thsT | im [ t \ and 115 lt ' s easy to employ air with safety at temperatures fur exceeding 
a the pressure of saturated steam would cease to be safe and manageable, 
fl| / ua ( !l ' rai,ni theoretical efficiency' of air-engines, consistent with safety, is much 
»l wi >1 n. ^ 8 ^-<mgines ; for example, nl the teraperuture of 650° Fahr., 
tom 'air a ' r * en S' ,ie has been successfully worked, the pressure of saturated 
^ on square inch, while that of air is optional, being regulated 
lathe B|ty at Which the « r is employed. 
yEinesl 8C< f SeCCiori l ^ e var ‘ ous causes of waste of heat and power in steam- 
anc * actua ' efficiency of steam-engines is compared with their 
rca “®° re tical efficiency, and also with the maximum actual efficiency which 
jtniohio “ , y ? e supposed to be attainable in the steam-engine by means of any 
CT d ' amcal ‘ m P r °vements. 
imlit v J e ing are Mutates of the consumption of bituminous coal of a specified 
r& e -^ r P er hour.— 
tenm “. oreticall y perfect engine, working between such limits of 
2, F or a dm “ S aie U8Uftl iu steam.engines..l‘861bs. 
extent ° ubc ‘ ac hng steam-engine improved to the utmost probable 
*• Fora weilV"; ...2-50 » 
Btinm ' cr ' 118tr ucted and properly worked ordinary double-acting 
, 111 CSd 8 ? 0,1 an .... 4-oo „ 
'• la «ilipd j n sectlou the causes of waste of heat and power in uir-engines are 
^ cier >cie s uf ,/ nanncr analogous to that upplied to steam-engines, and the actual 
■*"- been ohtr ° 5 V >reV ' OUa ft ‘‘'-engines us to which satisfactory experimental data 
Sli . , ' li . n s' 5 «**!"'• and F.ricsson’s engine of 1852, are 
Ur ° l ‘ hmits of t 1<; ”** c ‘ enc *es of theoretically perfect engines working between the 
^^mptioo 0 f em ? eia ' :uie ' the results being as follows, so far aa they relate to the 
coal of the specified quality, per horse-power per hour ;— 
Consumption of a 
Si;.]- , Actual consumption. theoretically 
K; D S B engine P crfctt engine. 
^'seneina^p';;: . 2’20lbs. O’fJlbs. 
Jt i» thug ] )rov fl8 ° 2 . 2'80lbs.* 0'82!bs. 
realh e ai'Aern 11 &n ail '- en gine has actually been made to work successfully, 
fc.*“ Ps « and, in p a .. f nom y °. f Fuel considerably superior to that of ordinary steam- 
tonvy 0 f T. surpBsstng the utmost limit to which it is probable that the 
■totengine as fiS St - >am * ensine8 can ewr be brought, 
lay rj le to get out of i. lm l )l ov e' I, was compact in its dimensions, easily worked, 
’‘ere „ m * en gine ■ Ktil/n *’ :uu * consu med less oil, and required fewer repairs than 
la great as to in l |° at J vail tagcs shown by that engine over steam-engines 
a iong-tiipd UCe , firoctlca) rae1 ' to overcome their natural repugnance 
bnu* ^ Flricsson'a m °tuod for a new one. Another circumstance caused 
"' e re by some ^'' gme8 lo racet with neglect from scientific men, namely, 
» r , ’"o'c popu|n.. . sons represented as instances of power created out of 
'^2V UCl C01 'U e di commonly called “ the perpetual,notion." 
^tplied' P fr hour, lc,w?. >S °" ° e ',‘ S T - WM a, ' lhrQ c>te. at the rate of 1*37 lb. per in- 
u toinj,l a . y. 1 * 5 , td reduce it .l 8 ,, 1 " 1 r °.'' I,0rton ' ! ' computation. This quantity is here 
* n ‘be other calrnia.- 1C ®q u,va ' ent quantity of bituminous coal of the quality 
«‘i.uiauons of this paper. 
