860 



SCIENCE. 



[N. S. Vol, XIV. No. 361. 



In determining the temperatures, the Cal- 

 lendar platinum instrument was employed ; but 

 a peculiar and ingenious special construction 

 was adopted to secure safety of the instrument 

 against injury by the action of the charge. 

 Among other interesting determinations made 

 with this thermometer, were the temperatures 

 of the charge at various distances from the 

 cylinder-wall. It was found that the charge 

 was distinctly hotter at the core than adjacent 

 to the metallic surface of the cylinder, the dif- 

 ference ranging from one to two hundred de- 

 grees centigrade. 



The gas used required 5.49 volumes of air for 

 combustion and produced 0.5672 volumes of CO 

 and 1.257 volumes of steam. After combustion 

 the volume is, total dry, 4,996. The weights 

 were, gas, per meter, 0.6 ; air, 1.29. Heating 

 values were 553 B. T. U. per cubic foot, 4,850 

 cal. per cubic meter. 



The engine was six inches by twelve and ran 

 at about 200 revolutions per minute and at 

 from 90 to 100 per cent, of its rated power ; 

 usually at about 95. The compression in Series 

 I. ranged up to from 200° C. to 300° C, and 

 the index of the compression-curve, pv'^ = C, 

 from 1.28 to 1.445 ; its maximum being found 

 at 311° C. ; but the irregularities of the figure 

 are too great to reveal any law. Probably 1.33 

 may be taken as the figure for approximate 

 computations. The expansion-curve value of 

 n = 1.4, as an average, or very nearly that, 

 ranging from 1.328 to 1.501. The mechanical 

 efficiency was from 68 to 80 per cent., averag- 

 ing about 75. 



In the final series of trials, with compression 

 ranging from 327° C. to 452° C. as maxima, 

 the index of the expansion-curve was about 

 1.3, varying from 1.2 with an exhaust tempera- 

 ture of 637° C. to 1.344 with a temperature of 

 exhaust of 862° C. The compression-curve 

 was less variable ; the index averaged very 

 nearly 1.35. The mechanical efficiency varied 

 from 0.64 to 0.83, and the thermal efficiency 

 from 18.1 to 22.7 per cent. 



The employment of compression produced, 

 on the whole, an increasing total efficiency 

 with increasing terminal pressure, though re- 

 ducing mechanical while augmenting thermo- 

 dynamic efficiency. From 13 to 16 per cent. 



of the heat-supply appeared as useful work out- 

 side the machine. The gas used ranged from 

 an average of 24.6 cu. ft. per I.H.P. per hour to 

 19.7, and from 34.9 per B.H.P. to 28.5. The 

 jacket carried away about 30 per cent, of the 

 heat developed, the exhaust about 45 per cent, 

 and radiation about 3. The heat-balance for 

 the most efficient case was 



I.H.P. Jack. Exh. Rad. Loss. Total. 

 23.1 + 30 4- 42.6 + 3 + 1.3 =: 100. 



R. H. Thurston. 



TSE NEW STAB IN PERSEUS. 



Professor W. W. Campbell, director of the 

 Lick Observatory has issued the following 

 bulletin : 



A discovery of extraordinary interest to as- 

 tronomers has just been made by Professor Per- 

 rine in reference to the new star in the con- 

 stellation Perseus. This star appeared sud- 

 denly and unexpectedly last February, having 

 been discovered by Anderson in Edinburgh. In 

 some four days its brightness increased from 

 invisibility in ordinary telescopes until it be- 

 came the brightest star in the northern sky. 

 All available astronomical resources through- 

 out the world were immediately devoted to the 

 investigation of this remarkable object. 



Many interesting facts concerning it have 

 been brought to light. To mention only a few, 

 its brightness diminished irregularly from that 

 of the most prominent star in the northern sky 

 in February until in June it was on the limit 

 of visibility /or trained and sensitive eyesights, 

 where it has since remained. The star's at- 

 mosphere was violently disturbed, as shown by 

 a study of its spectrum in the spring months and 

 since June, at least, the spectroscope has shown 

 that it is now a nebula, though retaining to the 

 eye and in the telescope the point-like form of 

 an ordinary star. The disturbance that gave 

 rise to the new star was sufficiently violent to 

 convert it from a dark invisible body into a 

 gaseous nebula. 



In August Professor. Max Wolf, of Heidel- 

 berg, Germany, secured a four-hour exposure 

 photograph of the region of the sky containing 

 the new star. His negative showed the exist- 

 ence of some extremely faint nebulous patches 



