LONGEVITY. 587 



On these figures the cost of electricity is near enough to that of gas 

 to enable it to offer a very substantial competition, and one which may 

 be expected to grow stronger with increased experience and future 

 improvements. That under the stimulus of this competition con- 

 siderable improvement will be made in lighting by gas seems very 

 probable. Already it has been shown that in the matter of burners 

 there is a wide field for invention, and that the results now usually 

 obtained are much under what are possible. With the high-power 

 burners of Siemens, the illumination obtained from sixteen-candle 

 gas has been more than doubled, and in others it has been carried up 

 to from five to five and a half candles per foot. How suitable burn- 

 ers yielding such a great increase of light will be for the general pur- 

 poses of lighting, and whether they can with advantage displace* the 

 simple flat tip, remains to be seen, but the present indications are that 

 it is chiefly through the use of improved burners that gas must en- 

 deavor to resist the assaults of the incandescent light. Competition 

 on the basis of a gas of higher illuminating power simply, without a 

 resort to improved burners, does not seem very promising. The re- 

 cently published report of the sub-commission, appointed to test the 

 incandescent lamps at the Paris Exhibition, of which Mr. Crookes was 

 a member, shows that a thirty-two-candle lamp can be maintained with 

 an increase of from 28 to 37 per cent of the power required to sustain 

 one of sixteen candles, while with gas such an increase of illumination 

 will require an additional expense of fully 50 per cent of the cost of 

 one of the lower candle-power. This is so with the Lowe gas, with 

 which three gallons of oil are sufficient to give sixteen candles, but 

 six are required for thirty-two, and it is not probable that coal-gas can 

 be enriched any cheaper. Whether the limit to progress in gas-light- 

 ing both in the matter of improvement of manufacture and burners 

 is sufficiently far off to give gas unquestioned possession of the field 

 of lighting or not, the result can alone determine. But, if the figures 

 presented in this paper can be at all relied upon, they show that gas- 

 manufacturers and those interested in gas property will do well not to 

 underrate the strength in their own domain of this rising industrial 

 power. 



-+++- 



LONGEVITY. 



By FELIX L. OSWALD, M. D. 



DURING his last expedition to Central Asia, Professor Vambery 

 managed to interview the Emir of Samarcand a sort of Mo- 

 hammedan prince-cardinal and primate of the Eastern Sunnites. As 

 Imam of the local ly^eum the Emir appeared to take a natural interest 

 in the progress of European science, but, when his guest expatiated on 



