308 



SCIENCE. 



[N. S. Vol. VII. No. 166. 



between the standard compound and stand- 

 ard triple-expansion engines, sometimes so 

 closely related to the latter that it becomes 

 a question whether the third cylinder of the 

 more complex machine may not be profit- 

 ably dispensed with. This question will be 

 answered in the negative or in the afiBrm- 

 a.tive, apparently, accordingly as the costs 

 of fuel are small or large, relatively to the 

 <;osts of the possibly superfluous cylinder. 

 With variable loads, also, the new type or 

 proportion of engine is found to give indi- 

 •cations of possessing some special ad- 

 vantages. 



Referring to the principles which must 

 ■control in any attempt to approximate more 

 closely to the best possible thermodynamic 

 eniployment of heat-energy, as transformed 

 in the steam-engine, the following are given 

 as the conclusions of the writers of the 

 paper, as the essential guides of the engi- 

 neer designing economical forms of steam- 

 engine. 



The Eequisites of Maximum Thermody- 

 namic EflSciency with Constant Load are : 



(1) A steam distribution approaching 

 most closely the ideal of Carnot ; or, assum- 

 ing the cycle of Rankine to be that in which 

 the machine is constructed to act, the closest 

 possible approximation to the ideal condi- 

 tions of distribution for that cycle. 



(2) As nearly as practicable, a non-con- 

 ducting cylinder, or its equivalent, a non- 

 heat-transferring working fluid, insuring, 

 approximately, at least, adiabatic action, 

 so far as heat transfers between working 

 fluid and enclosing walls are concerned. 



(3) Maximum possible range of pressure 

 and temperature during expansion. 



The Eequisites for Maximum Total Effi- 

 ciency are the above, together with : 



(4) Minimum friction of engine and heat- 

 losses. 



(5) Limitation of the expansion-range 

 by that volume at which the expansion line 

 meets the line, parallel with the back-pres- 



sure line, marking the sum of the use- 

 less resistance of the machine plus that 

 added quantity which is a fraction of 

 the mean effective pressure equal to the 

 ratio of the steam and heat wastes, in- 

 ternally and externally, due extra thermo- 

 dynamic causes, to the total steam and 

 heat supply. 



The Requisites for Maximum Commercial 

 Efficiency are, further : 



(6 J Such an adjustment of the propor- 

 tions and of the steam-distribution of the 

 engine that any change would cause a 

 larger loss in the dividend account than 

 would be saved by better conditions in the 

 direction in which improvement was 

 sought. 



PBESISTQBIC qUABTZITE QUARRIES IN CEN- 

 . TRAL EASTERN WYOMING. 



In July, 1894, while our scientific expedi- 

 tion was passing through eastern central 

 Wyoming, we came upon some prehistoric 

 quarries, which, owing to their number and 

 extent, are of more than usual scientific 

 interest. They are located some forty or 

 fifty miles north and east of Badger, a sta- 

 tion on the Cheyenne and Northern Rail- 

 road, one hundred and twenty-five miles 

 north of Cheyenne. There are no roads or 

 trails leading to this discovery, but the old 

 overland trail, following the north side of 

 the North Platte River, passes some four or 

 five miles west of the largest quarries. The 

 drainage from the quarries is to the north- 

 ward, into Muddy Creek, which flows west- 

 ward to the Platte River. In the vicinity 

 of the quarries the stream is dry, and water 

 is found running only in the spring and 

 during heavy rains. The country about is 

 very arid, and there is but a scanty supply 

 of both water and vegetation. 



Passing through this region from the 

 northeast to the southwest is a very promi- 

 nent bluff, with precipitous slopes facing 



