June 22, 1900.] 



SCIENCE. 



973 



tween boiler and condenser pressures, and 

 which, with the best of engines employing 

 saturated steam, amount to ten or twenty 

 per cent, and to a multiple of such figures 

 for small machines. The interior surfaces 

 of the turbine, in steady working, remain 

 at precisely the same temperatures and 

 absolutely without those fluctuations which 

 produce waste in the reciprocating, and in 

 the other forms of rotary, engine. As it is 

 to reduce this particular waste that super- 

 heating is employed, ordinarily, there would 

 not be expected to be found any other gain 

 by its use in the steam-turbine than that 

 increase of thermodynamic efficiency which 

 is due to the widened range of temperature, 

 in this case amounting to about one-tenth 

 of one per cent, per degree of superheat. 

 Investigations by -Messrs. Schieren and 

 Thomas, above alluded to, show, on the con- 

 trary, a gain of about one per cent, for each 

 one and two-thirds degrees, C, three Fahr- 

 enheit degrees, of superheat and the remark- 

 able and unexpected result of an increase in 

 the capacity of the machine of about one 

 hundred per cent, by the use of but 20° C, 

 37° Fahr., superheat. The ' water-rate ' of 

 the turbine, a La Val machine of ten horse- 

 power as rated, decreased from about 21 .7 

 kgs., 48 lbs., to 1.99 kgs., 44 lbs, with pres- 

 sure rising from three atmospheres to eight, 

 with a two-thirds vacuum, and with satu- 

 rated steam ; while the figures fell off about 

 12 per cent, with superheating, rising to a 

 very moderate maximum as above. Ee- 

 duced to thermal units per horse-power per 

 hour, the same effect appears in a very sim- 

 ilar proportion. The causes of the gain in 

 thermodynamic efficiency and of capacity 

 are pi-esumably identical — the extinction of 

 the friction-wastes due to the retardation 

 of the current of fluid traversing the pas- 

 sages of the turbine by concurrent resist- 

 ances coming of the weighting of the current 

 of steam with drops and mist and the ad- 

 herence of moisture in mist, drops and even 



streams, very probably, to the walls of the 

 steam-passages of the turbine. The phe- 

 nomenon will however, be the subject of 

 extended investigation in the course of the 

 work in research constantly in progress and" 

 a way will probably be found of precisely 

 identifying the cause and determining the 

 laws governing its action in the production 

 of these variations of efficiency and capacity. 

 That this apparently obvious explanation is 

 the correct one and, certainly, that the gain 

 is not due any such action as produces the 

 remarkably beneficial effects observed in the 

 reciprocating engine, is tolerably well indi- 

 cated by the fact that the gain in this case, 

 by superheating, is substantially propor- 

 tional, so far as here carried, to the amount 

 of superheat and the graphic log shows a 

 straight line of decreasing consumption of 

 steam. 



R. H. Thurston. 



THE MOBINGUOID EELS IN A3IERICAN 

 WATERS. 



Notwithstanding the numerous eels 

 which have been discovered in American 

 waters, none has yet been found which has 

 been referred to the family of Moringuidm. 

 Indeed, from the literature it would appear 

 that the group was peculiar to the seas of 

 India and the Molucca-Indian archipelago. 

 However, Dr. Smith recently received from 

 Mr. George M. Gray, of "Woods Hole, an 

 eel found in branching coral at San Gero- 

 nimo, near San Juan, on the north shore of 

 the island of Porto Eico, which he was at 

 a loss to allocate and took it to Dr. Gill. 

 The latter was struck by its resemblance to 

 Aphthahnichthys, and the subsequent compar- 

 ison with the figures of Bleeker's 'Atlas Ich- 

 thyologiques des Indes Orientales Neerlan- 

 daises ' revealed no differential characters 

 to separate it from that genus. Further, a 

 consideration of the very elongated whip- 

 like forms referred by Jordan and Evermann 



