664 



SCIENCE. 



[N. S. Vol. I. No. 24. 



ment. The group is essentially a tropical 

 one, unknown in Europe and with onlj' one 

 species (as recognized by Brunner) in the 

 United States^-our true Katydid. Others 

 will doubtless be found upon our southern 

 borders, for in Mexico, Central America 

 and the Antilles Brunner recognizes 34 gen- 

 era and 73 species, the larger part of them 

 new. The work, which is published in Vi- 

 enna in 8°, contains descriptions of 434 spe- 

 cies, divided among 122 genera, and is ac- 

 companied by a quarto atlas of ten plates. 



A NEW QUADRUPLE EXPANSION ENGINE. 



Messes. Hall and Treat announce, in the 

 Sibley Journal of Engineering for April, ' A 

 New Quadruple Expansion Engine.' This 

 machine, built for regular working at 500 

 pounds pressure, and with its boiler, tested 

 to 1300 pounds, has now been in operation 

 in Sibley College, at Cornell University, for 

 many months. It was designed by the au- 

 thors of the paper, built by them in the 

 shops of the College, and has since been 

 tested under a great variety of conditions. 

 The design was entirely original, although, 

 of course, embodying the principles taught 

 them in their college course, the one being 

 a graduate of '93 and the other of '94, and 

 both now candidates for advanced degrees, 

 the one for a doctor's, the other for the 

 master's, degree in engineering. The valve- 

 gear is new and the invention of the build- 

 ers of the engine. The proportions of the 

 multiple-cylinder system are those derived 

 by application of their text-book and lec- 

 ture-room work ; and the engine as a whole 

 is a success. The boiler has worked well 

 and' economically up to above 600 pounds 

 per square-inch, and its waste heat is util- 

 ized in the re-heating apparatus of the 

 engine and so thoroughly as to make the 

 temperature of the chimney very low. The 

 steel for ' running parts' was obtained from 

 the Bethlehem Iron Company and proves 

 to be of very fine quality. Special devices 



have been required, in eveiy dii-ectiou, to 

 make the operation of the machine with such 

 high-pressure steam satisfactory and safe. 

 Even the injector was necessaril}' recon- 

 structed, as no ordinary instrument would 

 force water iato the boiler against 600 

 pounds pressure. The figures reported for 

 economy are something under ten pounds of 

 steam per h. p. per hour, and the best condi- 

 tions of operation are not yet fully identi- 

 fied, though unquestionably corresponding 

 closely with the preliminary computations 

 of the designers. This figure is the lowest 

 yet reported, even for engines of many 

 times the size of that here described. It 

 will require authoritative revision and cor- 

 roboration ; but there seems no reason to 

 doubt its substantial accuracy, as the result 

 of many engine-trials under a great variety 

 of conditions. If thus corroborated, it will 

 stand as the ' record of the world' for the 

 nineteenth century. The thermodynamic 

 consumption of this engine should be about 

 7 pounds of steam per h. p. per hour, exclu- 

 sive of all thermal wastes, and this should 

 be approximated much more closely in en- 

 gines of similar type built on a large scale. 

 The figure attained is extraordinary, and 

 almost incredible, for a model engine such 

 as is described ; yet it indicates a waste, by 

 conduction and radiation, after all, of no 

 less than twenty-five per cent, of all heat 

 sent to the machine from its boiler. 



PAPERS FOR THE MATHEMATICAL CONGRESS 

 AT KAZAN. 



On the occasion of the dedication of the 

 Lobachevski monument at Kazan will be 

 held a mathematical congress of a week's 

 duration. 



It is very much desired by the manage- 

 ment that some papers may be contributed 

 by Americans. As a complete program of 

 the scientific communications to be made in 

 the session will be issued this coming Feb- 

 ruary, it is not too early to solicit Ameri- 



