70 
NATURE 
[Mov. 16, 1882. 
secondary batteries should become more permanent in their action 
than they are at the present time, they may be largely resorted 
to by consumers, to receive a charge of electrical energy during 
the dey time, or the small hours of the night, when the central 
engine would otherwise be unemployed, and the advantage of 
resorting to these means will depend upon the relative first cost, 
and cost of working the secondary battery and the engine respec- 
tively. These questions are, however, outside the range of our 
present consideration. 
The large aggregate of dwellings comprising the metropolis of 
London covers about seventy square miles, thirty of which may 
be taken to consist of parks, squares, and sparsely inhabited 
areas, which are not to be considered for our present purpose. 
The remaining forty square miles could be divided into say 140 
districts, slightly exceeding a quarter of a square mile on the 
average, but containing each fully 3,000 houses, and a population 
similar to that of St. James’s. 
Assuming twenty of these districts to rank with the parish of 
St. |ames’s (after deducting the 600 shops which I did not in- 
clude in my estimate) as central districts, sixty to be residential 
districts, and sixty to be comparatively poor neighbourhoods, 
and estimating the illuminating power required for these three 
classes in the proportion of 1 to % to 4, we should find that the 
total capital expenditure for supplying the metropolis with 
electric energy to the extent of 25 per cent. of the total lighting 
requirements would be— 
20 x 177,000 = 3,540,000/. 
60 x % x 177,000 = 7,080,000/. 
60 x 4 x 177,000 = 3,540,000/. 
14, 160,000/, 
and making an average capital expenditure of 100,000/. per 
district. 
To extend the same system over the towns of Great Britain, 
and Ireland would absorb a capital exceeding certainly 
64,000,000/., to which must be added 16,co0,000/. for lamps 
and internal fittings, making a total capital expenditure of 
80,000,000/, Some of us may live to see this capital realised, 
but to find such an amount of capital, and, what is more im- 
portant, to find the manufacturing appliances to produce work 
representing this value of machinery and wire, must necessarily 
be the result of many years of technical development. If, 
therefore, we see that electric companies apply for provi-ional 
orders to supply electric energy, not only for every town through- 
out the country, but also for the colonies, and for foreign parts, 
we are forced to the conclusion that their ambition is somewhat 
in excess of their power of performance ; and that no provisional 
order should be granted except conditionally on the work being 
executed within a reasonable time, as without such a provision 
the powers granted may have the effect of retarding instcad of 
advancing electric lighting, and of providing an undue en- 
couragement to purely speculative operations, 
The extension of a district beyond the quarter of a square mile 
limit, would necessitate an establishment of unwieldy dimen- 
sions, and the total cost of electric conductors per unit area 
would be materially increased ; but independently of the consider- 
ation of cost, great public inconvenience would arise in 
consequence of the number and dimensions of the electric 
conductors, which could no longer be accommodated in narrow 
channels placed below the kerb stones, but would necessitate 
the construction of costly subways—veritable cava electrica. 
The amount of the working charges of an establishnient com- 
prising the parish of St. James’s would depend on the number 
of working hours in the day, and on the price of fuel per ton. 
Assuming the 64,000 lights to incandesce for six hours a day, 
the price of coal to be 20s. a ton, and the consumption 2lbs. per 
effective horse power per hour, the annual charge under this 
head, taking eight hours’ firing, would amount to about 18, 300/., 
to which would have to be added for wages, repairs, and sundries, 
about 6,000/., for interest with depreciation at seven-and-a-half 
per cent., 13,300/., and for general management say, 3,400/., 
making a total annual charge of 41,000/., or at the rate of 
12s. 94d. per incandescent lamp per annum. To this has to be 
added the cost of renewal ot lamps, which may be taken at 55. 
per lamp of sixteen candles, lasting 1,200 hours, or to 9s. per 
annum, making a total of 21s. 94d. per lamp for a year. 
In comparing these results with the cost of gas-lighting, we 
shall find that it takes 5 cubic feet of gas, in a good argand 
burner, to produce the same luminous effect as one incandescent | 
light of 16-candle power. In lighting such a burner every day 
for six hours on the average, we obtain an annual gas consump- 
tion of 10,950 cubic feet, the value of which, taken at the rate 
of 2s. 8d. per thousand, represents an annual charge of 29s., 
showing that electric light by incandescence, when carried out 
ona large scale, is decidedly cheaper than gas-lighting at present 
prices, and with the ordinary gas-burners. 
On the other hand, the cost of establishing gas-works and 
mains of a capacity equal to 64,000 argand burners would 
involve an expenditure not exceeding 80,000/, as compared with 
177,000/, in the case of electricity ; and it is thus shown that 
although it is more costly to establish a given supply of illu- 
minating power by electricity than gas, the former has the 
advantage as regards current cost of production. 
It would not be safe, however, for the advocates of electric 
lighting to rely upon these figures as representing a permanent 
state of things. In calculating the cost of electric light, I have 
only allowed for depreciation and 5 per cent. interest upon 
capital expenditure, whereas gas companies are in the habit of 
dividing large dividends, and can afford to supply gas at a 
cheaper rate, by taking advantage of recent improvements in 
manufacturing operations, and of the ever-increasing value of 
their by-products, including tar, coke, and ammoniacal liquor. 
Burners have, moreover, been recently devised by which the 
luminous effect for a given expenditure of gas can be nearly 
doubled by purely mechanical arrangements, and the brillianey 
of the light can be greatly improved. 
On the other hand, electric lighting also may certainly be 
cheapened by resorting, to a greater extent than has been 
assumed, to are lighting, which though less agreeable than the 
' incandescent light for domestic purposes, can be produced at 
or say 14,000, 000/., without including lamps and internal fittings, | 
less than half the cost, and deserves on that account the prefer- 
ence for street lighting, and for large halls, in combination with 
incandescent lights. Lamps by incandescence may be produced 
hereafter at a lower cost, and of a more enduring character. 
Considering the increasing public demand for improved illu- 
mination, it is not unrezsonable to expect that the introduction 
of the electric light to the full extent here contemplated, would 
go hand in hand with an increasing consumption of gas for 
illuminating and for heating purposes, and the neck-to-neck 
competition between the representatives of the two systems of 
illumination, which is hkely to ensue, cannot fail to improve the 
quality, and to cheapen the supply of both, a competition which 
the consuming public can affurd to watch with complacent self- 
satisfaction. Electricity must win the day, as the light of 
luxury ; but gas will, at the same time, find an ever-increasing 
application for the more humble purposes of diffusing light. 
In my address to the British Association I dwelt upon the 
capabilities and prospects of gas, both us an illuminant and asa 
heating agent, ani I do not think that I was over-sanguine in 
predicting for this combustible a future exceeding all present 
anticipations. 
T also called attention to the advantages of gas as a heating 
agent, showing that if supplied specially for the purpose, it 
would become not only the most convenient, but by far the 
cheapest form of fuel that can be supplied to our towns. Such 
a general supply of heating separately from illuminating gas, by 
collecting the two gases into separate holders during the process 
of distillation, woulda have the beneficial effects— 
I. Of giving to lighting gas a higher illuminating power. 
2. Of relieving our towns of their most objectionable traffic— 
that in coal and ashes. 
3. Of effecting the perfect cure of that bugbear of our winter 
existence—the smoke nuisance. 
4. Of largely increasing the production of those valuable by- 
products, tar, coke, and ammonia, the annual value of which 
already exceeds by nearly 3,000,000/, that of the coal consumed 
in the gas-works, 
The late exhibitions have been beneficial in arousing public 
interest in favour of smoke abatement, and it is satisfactory to 
find that many persons, without being compelled to do so, are 
now introducing perfectly smokeless arrangements for their 
domestic and kitchen fires, 
The Society of Arts, which for more than Ioo years has given 
its attention to important questions regarding public health, 
comfort, and instruction, would, in my opinion be the proper 
body to examine thoroughly into the question of the supply and 
economical application of gas and electricity for the purposes 
of lighting, of power production, and of heating, They would 
