June 14, 1906J 



NA TURE 



165 



Table I. — TahXc of Apparent Specific Heats {Instantaneous) 

 in foot-pounds per cubic foot of Working Fluid at 

 0° C. and 760 mm. 



100 

 200 

 300 

 400 

 500 

 600 

 700 



Specific heat at 



constant volume 



ft.-lbs. 



196 



20-9 



22-0 



230 



239 



24-8 



25-2 



257 



•c. 

 800 

 900 



1CX)0 



1 100 

 1200 

 1300 

 1400 

 1500 



Specific heat : 

 constant volun 



ft.-lbs. 



262 



26-6 

 268 

 27 o 



27 -2 

 27 3 

 27-35 

 27-45 



T.^BLE TI. — Table of Mean Apparent Specific Heats in foot- 

 pounds per cubic foot of Working Fluid at o° C. and 

 7()0 mm. 



The curves of heat loss show that for equal temperature 

 differences heat loss per unit surface exposed increases 

 with density, and values are given of the heat losses for 

 various temperatures. From these curves mean tempera- 

 tures of the cylinder walls have been calculated, and shown 

 to vary at full load from 190" C. for the whole stroke to 

 400° C. for the three-tenths stroke. 



Calculations are made of heat distribution in the work- 

 ing cycle of the fluid which show that the total heat 

 present in the form of combustible gas can be accurately 

 calculated from the indicator diagram alone, by means of 

 the new data obtained in the investigation. 



It is pointed out that with a sufficiently sensitive 

 indicating instrument the rate of continued combustion 

 can be determined, and the true change of specific heat 

 obtained from experiments made by the new method. 

 The determination of the specific heat of gases heated by 

 high compressions, such as one and a half tons to the 

 square inch, is suggested, to avoid the complications intro- 

 duced by combustion. It is shown that in these experi- 

 ments the rate of loss of a mass of flame at iooo° C. to 

 the comparatively cold walls of the cylinder was less than 

 the rate of addition of heat by work performed by the 

 piston, so that the flame temperature in the first com- 

 pression rose from 1000° C. to about 1300° C, that is, 

 compression in 025 second enabled a mass of flame to be 

 handled in such a manner as to obtain accurate results. 

 In these experiments, with maximum pressures of four 

 hundred pounds per square inch, nearly twenty-eight tons 

 total pressure was applied from 120 to 160 times per 

 minute. 



Mallard and Le Chatelier's experiments are discussed, 

 and it is shown that no curve of specific heat can be 

 deduced from their observations. It is pointed out that 

 the curve of apparent change of specific heat of certain 

 gases from 0° C. to 1500° C. has been here determined 

 experimentally for the first time. The gases forming the 

 working fluid consist mainly of carbonic acid, steam, 

 nitrogen, and oxygen. The composition and all other 

 details are given in the paper. 



Anthropological Institute, May 22.- Prof. W. Gnwiand, 

 president, in the chair.— (i) A series of slides of stone 

 monuments found in .Assam; (2) a paper on the " genna " 

 (tabu) among the tribes of Assam: T. C. Hodson. The 

 tabus are of two kinds, general or communal, as contrasted 

 with private or individual tabus. Communal tabus are 

 observed by the whole village, which consists of several 

 exogamous subdivisions, and are automatic, in the sense 

 that they are of regular occurrence or necessarily follow 

 the occurrence of some event. These regular tabus are 

 mostly connected with the crops, and are frequently times 

 NO. IQI I, VOL. 74I 



of great license. The village is made genna before the 

 crop is sown, at the harvest-home, and sometimes on the 

 appearance of the first blade ot the crop. When the village 

 is genna everyone must stay in until the tabu is over, and 

 it sometiines lasts as long as ten days, and no one who is 

 outside is allowed to come in. The village is also genna 

 when a rain-making ceremony is necessary, and, in fact, 

 any magical ceremony for the good of the whole com- 

 munity is necessarily accompanied by a general genna. 

 Gennas are also occasioned by natural phenomena, such 

 as earthquakes, eclipses, &c., and when the annual cere- 

 mony of laying the ghosts of those who have died within 

 the year is held. Individual gennas are necessary at all 

 important events in life, such as childbirth or marriage, 

 and are as inevitable as crop gennas. They are also ex- 

 tended to certain foods, especially in the case of the head 

 man of the village, and are also necessary when any per- 

 son wishes to erect a monolith, usually for self-glorification. 

 Such an individual is genna from the moment he takes 

 the first steps towards erecting a monolith until the stone 

 is finally in position. Slides of these monuments were 

 shown by Mr. Hodson earlier in the evening. Gennas are 

 also occasioned by the birth or death of any animal within 

 the house, and warriors before and after a raid are subject 

 to the-n. 



Geological Society, May 23. — Mr. R. .S. Ilerries, vice- 

 president, in the chair. — The importance of Ilalimcda as 

 a reef-forming organism, with a description of the 

 Halimeda-Limestones of the New Hebrides : F. Chapman 

 and D. Mawson, Calcareous algre, nuUipores, Litho- 

 thamnion, &c., have been frequently referred to as forming 

 important contributions to the rock of coral-reefs. The 

 material obtained in the great boring, the lagoon borings, 

 and lagoon dredging at Funafuti has yielded a considerable 

 quantity of Halimeda, and Dr. Guppy has described a 

 Halimeda-Limestone in the Solomon Islands. Evidence 

 such as this shows that the important deposits of calcareous 

 plant-remains forming at the present day can scarcely be 

 paralleled by any deposit formed in past geological limes 

 e-xcept, possibly, the limestones of the .Alpine Trias, which 

 owe their origin to the thallophytes Diplopora and Gyro- 

 porella. Among other Halimeda-Limestones mentioned by 

 the authors are those of Christmas Island, Fiji and Tonga, 

 and the New Hebrides. — Notes on the genera Omospira, 

 Lophospira, and Turritoma, with descriptions of new 

 species : Miss Jane Donald. The new species described 

 in the paper belong to three genera, characterised by the 

 possession of a band on all the whorls formed by the 

 gradual filling up during growth of a sinus, and not a 

 slit, in the outer lip. — Lantern-slide views illustrating the 

 late eruption of Vesuvius and its effects : Prof. H. J. 

 Johnston-Lavis. Nearly all the photographs were taken 

 by the exhibitor, who explained the different phenomena 

 portrayed. He considered this eruption to resemble mostly 

 that of 1822, although the present crater was larger, 

 attaining 1500 feet both north-by-soulh and east-by-west; 

 it was probably 500 feet to 600 feet deep at least. The re- 

 markable character about this eruption was the large 

 amount of fragmentary material ejected, especially in a 

 north-easterly direction, crushing in the roofs of the build- 

 ings in the towns of Ottajano, San Giuseppe, and Terzigno. 

 At the first-named locality the depth attained was nearly 

 075 metre, made up as follows : — 004 m. grey dust, 

 049 m. reddish lapilli, chiefly " supplementary ejecta," 

 0-20 m. black vesicular scoria, chiefly the " essential 

 ejecta." The material which fell at the observatory and 

 Naples had much the same arrangement, but was, of 

 course, less, and practically only sand and dust. Near the 

 base of the cone the ejecta attain to blocks several tons in 

 weight ; and it may be estimated that, at the north-eastern 

 toe of the great cone, in some places, the debris must be 

 60 feet thick. It is to be seen as much as 30 feet in thickness 

 in the new ravines that have been formed. After careful 

 study. Prof. Johnston-Lavis had come to the conclusion that 

 the remarkably uniform and deep scoring of the cone by 

 very regular " barrancos " was due to the sliding and 

 avalanche-like effect of the rapidly accumulating fragmentary 

 material on the steep slopes, and not due to water-action. 

 The volcano seems to have opened at four, if not five, 

 different places on the south-western, southern, and south- 



