146 



NATURE 



[June 12, 1890 



as nearly all the houses had cellars under the public 

 street ; but for the last two years the town has been 

 lighted by means of electricity. The price charged is 

 either at a fixed rate per month, independently of the 

 number of hours the lamp is lighted, or the consumer 

 can pay for the actual time the lamps are used at the rate 

 of 5 J centimes per hour for a i6-candle lamp, 4 centimes 

 for a lo-candle lamp, and 3^ centimes if the lamp be of 

 8 candles. It'is interesting to notice that this charge of 

 5i centimes per hour for a i6-candle lamp is almost 

 exactly equivalent to M. per Board of Trade unit— the 

 legalized rate for London. 



At Perpignan, the prices per hour per lamp are the 

 same as at Manosque, but if the lighting be charged at a 

 fixed rate per month, the rate for a lo-candle lamp is 

 either 3A or 6 or 8 francs per month, depending on 

 whether the lamp is put out every night at 10 o'clock 

 or at midnight, or is left alight all night. 



In Paris, gas costs 30 centimes per cubic metre, or, 

 roughly, ^s. 6d. per icoo cubic feet, while, for a lo-candle 

 glow-lamp, 4-8 centimes per hour is charged ; the user 

 has also to pay an annual subscription of 4 francs, and 

 he has to replace his lamp after 1000 hours at a cost of 

 4 francs. With these figures the author concludes that 

 electric lighting with glow-lamps is 40 per cent, dearer 

 than lighting with gas. 



The largest single electric installations of <?/-^-lamps is 

 at Brooklyn, in America, where the Thomson-Houstin 

 Company supply current for 1325. The following the 

 author gives as the prices paid per hour for the current 

 for one arc-lamp : — 



To enable a comparison to be made, we have ascertained 

 that the yearly price charged for the arc-lamps on the 

 Parades of the English watering-places is equivalent to 

 about 35 centimetres per arc-lamp per hour. 

 ^ M. Jules Couture concludes his treatise in a very judi- 

 cious manner as an old director of the Marseilles Gas 

 Company :— " Little Jack Gas lives still, and will continue 

 to live, I hope, for a long time yet. To prolong its exist- 

 ence, gas will not hesitate to inscribe on its banner, 

 ' Gas-Electricity,' because its advocates are not at all 

 adverse to progress." 



The treatise forms a handy reference-book for those in- 

 terested in the progress of electric lighting. It would have 

 been well, however, if the author had given the price of 

 electric energy in the various towns, instead of the price per 

 ampere or the price for the current for a particular lamp. 

 Constant reference is made to the supply of the light '^ au 

 moycn de compteurs" in the various towns. Electrical 

 engineers would have gladly welcomed some information 

 as regards the character and the behaviour, satisfactory 

 or otherwise, of the meters employed. We have already 

 said that we think statistics of electric lighting in Great 

 Britain might well have been added, seeing that it is now 

 nearly two years ago since the Englishman's backward- 

 ness in taking up electric lighting began to disappear. 



In justice to the consumers of gas, more stress should 

 have been laid on the fact that ordinary gas-burners are 

 NO. 1076, VOL. 42] 



very inefficient things. It might, for example, have been 

 pointed out that, while as much as 6 candles per cubic 

 foot of gas consumed per hour can be obtained with a 

 Welsbach or with an albo-carbon burner, as little as i of 

 a candle per cubic foot consumed per hour is the meagre 

 efficiency of certain twopenny-halfpenny nondescript 

 burners. And if such a nondescript burner be un- 

 governed, as it probably will be, since people who have 

 not the sense to buy good gas-burners are not likely to 

 buy governors for them, then, when the pressure of the 

 gas rises in the mains, the burner will not give more than 

 i a candle per cubic foot. So that a burner passing 5 

 cubic feet of London gas per hour may give any illumina- 

 tion from 3 to 30 candles, depending on the nature of the 

 burner. 



In dealing, therefore, with the vexed question of the 

 relative cost of lighting with electricity and gas, we 

 must remember that, apart from glow-lamps causing 

 much less damage than gas to books and decorations of 

 rooms, lighting with glow-lamps at ?>d. per Board of Trade 

 Unit costs no more than lighting with ungoverned common 

 gas-burners using gas at 2s. 6d. per thousand cubic feet. 

 On the other hand, lighting with glow-lamps costs about 

 3 times as much as lighting with governed Argand 

 burners, and 4 or 5 times as much as using albo-carbon 

 or Welsbach burners. 



A TEXT- BOOK OF GEOLOGY. 

 The School Manual of Geology. By J. Beete Jukes, 

 F.R.S. Fifth Edition. Edited by A. J. Jukes- 

 Browne, B.A., F.G.S. (Edinburgh: A. and C. 

 Black, 1890.) 



THE title and success of this handy little book lead 

 one to inquire how far and where geology is taught 

 in schools. There is no doubt that the subject has for 

 scholars, particularly in the country, the strongest fascina- 

 tion ; and the fine museum of Marlborough is an example 

 of how " natural history " studies may bs kept alive in 

 seats of youthful learning. But it would be interesting 

 to know how many schools, excluding special evening- 

 classes, can give such a work as this a place in their 

 curriculum, and thus carry back the history of England, 

 Rome, and Greece to the earliest dawn of life upon the 

 globe. The preliminary training for the appreciation of 

 geological features such as every lad can see around him 

 need not be excessively severe ; the mere appreciation is 

 at first the great thing — the knowledge that there is some- 

 thing to be learnt in road-side quarries, in familiar 

 hollows of the hills, beside which the "Dictionary of 

 Antiquities " seems like a fashion-book of yesterday ; 

 while at the same time, perhaps, the kinship of the 

 boy with his favourite classic hero becomes something 

 more real and inspiriting in face of the enormous past 

 beyond them both. 



While the work before us is a concise and convenient 

 text-book, we suspect that, from mere force of circum- 

 stances, it aims more at the individual student than at 

 the school-boy and the class. Just as W^illiam Smith, at 

 the beginning of the century, pleaded for geology as a 

 study advantageous to land-owners, so the editor appeals 

 in his preface to the practical good sense of parents. The 



