248 



SCIENCE. 



[N. S. Vol. XVTII. No. 451. 



batics, have the efficiency (T^ — T„)/T^, where 

 Tj and T„ are the temperatures of the ter- 

 minals of the compression line. 



Adopting the methods of the writer, the 

 following data are obtained.* 



ordinates to pressure, volume and temperature 

 planes. The two cycles are seen in usual 

 form on the p-v plane and their respective 

 diagrams are indicated throughout the figure 

 by full lines for the Carnot, dotted lines for 



Chabacteeistics of Type-Cycles. 



Carnot 15 



Otto 15 



Brayton 15 



Ericsson 15 



Stirling 15 



Absolute Pressure 

 Lbs. per sq. in. 



115 

 115 

 115 



72.3 



72.3 133 



23.8 

 188.3 

 115 



72.3 



3.11 

 24.5 

 15 

 15 

 27 



Absolute Temperature. 



520 

 520 

 520 

 520 



931 

 931 

 931 

 520 



931 

 1522.7 

 1352.7 



931 



931 



520 

 852 

 755 

 931 



Carnot . , 

 Otto ... 

 Brayton 

 Ericsson 

 Stirling 



.2334 



.2334 



.2334 



.207 



.207 



1.125 

 .233 

 .338 

 .372 

 .207 



4.82 



1 



1.45 



1.79 



1 



Maxi- 

 mum 

 Pressure. 



115 

 188.3 

 115 

 73 

 130 



Maxi- Maxi- 

 mum mum 

 Tempera- Volume, 

 ture. 



931 

 1522.7 

 1352.7 



931 



931 



4.83 

 1.00 

 1.45 

 1.00 

 1.80 



The characteristics of the several cycles are 

 displayed graphically in the usual manner on 

 pressure-volume, on temperature-volume, and 

 on temperatiire-entropy planes, aU of which 

 bring out very clearly the distinctions indi- 

 cated by the tabulated data; the principal 

 being the great volume of the working cylinder 

 for the Carnot cycle, the comparatively large 

 pressures of the Otto — the Beau de Eochas — 

 and the low pressures of the Ericsson diagram. 

 The Carnot cycle is thought impracticable on 

 account of engine volume, weight and cost ; the 

 Beau de Eochas involves very high tempera- 

 tures and pressures and the Ericsson and 

 Stirling engines seem likely to waste largely 

 by dissipation of heat. 



" The Brayton, on the whole, seems to 

 promise best and, while practical obstacles 

 modify any application, it yet remains true 

 that recent reports would seem to place en- 

 gines operating in this cycle in the lead." 



The most novel and perhaps immediately 

 interesting feature of the paper is its illustra- 

 tions of the cycles discussed by forms in relief. 

 The accompanying engraving is an illustra- 

 tion of one of these — a comparison of the 

 Carnot and the Brayton cycles, referring co- 



* Manual of the Steam-Engine,' Vol. I., p. 418. 



Brayton. The numerals 1 and 1„, 2 and 2„, 

 3 and 3,,, respectively, indicate the same dis- 

 tinction. The common initial point of the 

 diagrams is seen at 0. 



E. H. Thurston. 



EXHIBIT OF THE V. 8. NATIOiSlAL SIVSEVM 

 AT ST. LOUIS. 

 The most striking feature of the exhibit 

 of the U. S. National Museum at St. Louis 

 will be the reproduction of a full grown sul- 

 phur-bottom whale. The mold for this was 

 obtained through the courtesy of the Cabot 

 Steam Whaling Co. at their station at Balena, 

 Newfoundland, and was made from one of the 

 largest whales taken this summer; a skeleton 

 of the same species was presented by the 

 Colonial Manufacturing Co., of St. Johns, 

 Newfoundland. As definite measures and 

 weights of whales are not easily obtainable 

 some details on these points may be of interest. 

 The animal, a male, from which the skeleton 

 was procured, measured 74. ft., 8 in. from the 

 notch of the flukes to the tip of the nose, or 

 79 ft. from tip of flukes to tip of lower jaw. 

 The girth around shoulders was 35 ft. and the 

 width of the flukes 16 ft., 5 in. The skull, 

 over all, measured 19 ft. and the width across 



