1879.] 
its Practical Results in London . 
295 
£5 per light for the sixteen lamps, the cost per lamp is 
10s. 7^. per hour, or about £3072 per annum for 4300 hours ; 
the eighty-six gas-lights originally used costing during the 
same period £419, which is about two-fifteenths of the 
major sum. Colonel Haywood seems to have made no 
photometric experiments on the ViaduCt light ; his estimate 
that the sixteen eleCtric lights give out about seven times 
more light than the eighty-six gas-burners is based on the 
observations of others. It will be seen from this that 
Colonel Haywood’s data of the relative value of the two 
kinds of light are somewhat hazy ; it would be interesting 
to compare his figures with those contained in the report of 
his confrere , M. Cernesson, Surveyor to the Paris Munici- 
pality, but the exigencies of space prevent it. 
The lighting of the City thoroughfare was as successful in 
its way as that of the Embankment; the passage of the 
wayfarer from the yellow gloom of Newgate Street into the 
“ sweetness and light ” of the ViaduCt was hardly more 
striking than his emergence out of the gentle moonlight 
of the Jablochkoff candles into the darkness visible of 
Iiolborn. 
The third experiment was a highly successful one, and 
proved most satisfactorily that by employing a sufficient 
number of lights the British Museum Reading-Room might 
be made available to readers by night as well as by day. 
Fifteen out of the nineteen reading-desks were lighted by 
eleven candles, enclosed in an opal globe, and placed on a 
pedestal 15 feet high, fixed in the exaCt centre of each desk, 
a twelfth lamp being placed in the centre of the room : four 
of the desks were consecutively lighted, the remainder 
alternately. The reading-room was kept open until 7 o’clock 
on the evenings of the 3rd, 4th, and 5th of March, in order 
that the new light might be thoroughly tested in a practical 
manner by those for whose benefit the experiment had been 
made. The readers showed their hearty approval of the 
innovation by remaining behind in considerable numbers. 
On the first night a strange incident occurred. At a few 
minutes before 6 o’clock, when the twelve Jablochkoff 
candles suddenly flashed forth, the readers, led by a well- 
known poetess, and forgetting they were in the reading- 
room, evinced their admiration of the beauty of the light 
by a burst of applause — a sound hitherto unknown under 
that dome of silence. 
Mr. E. A. Bond, the Principal Librarian of the British 
Museum, to whose initiative these experiments are due, has 
been at some trouble to collect information as to the opinion 
