1879*] 
Notes. 
775 
dynamo-eledtric machine, with a separate exciter, driven very fast 
with a steam-engine, or with a stream of water, at high or low 
pressure, and sending, by even quite a fine wire, a small current 
to a distant eledlro-motor, also running very fast and magnetised 
by a separate exciter, is an economic arrangement for the trans- 
mission of power. As an illustration of what had been done by 
electricity as a motive power, Prof. Ayrton referred to the experi- 
ments of MM. Chretien and Felix, who last year at Sermaize 
(Marne) ploughed fields by electricity, the eledtric current being 
produced by two of Gramme’s dynamo-eledtric machines. These 
machines were usually worked with a sceam-engine at some 
convenient place 300 or 400 yards away, in an adjoining road. 
The eledtro-motors were also two Gramme machines, one on 
each side of the field, with their coils revolving backwards. 
Through one of these the electric current was sent alternately, 
so that motion was given to one or other of two large windlasses, 
one on each of the waggons containing the eledtro-motors. In 
this way the plough, which could be used going in either direc- 
tion, was first pulled across the field, making a furrow, and then 
back again, making another parallel furrow. M. Chretien’s 
eledtric crane has also been successfully employed for several 
months at Sermaize, in the harbour there, and it is considered 
that a saving of about 30 per cent has been effected of the 
expense formerly incurred for unloading the sugar-barrels out of 
the boats. Calculation showed that if eleCtric currents — gene- 
rated by very large steam-engines at certain points, and by 
turbines driven by the falling water on the hill-sides around 
Sheffield — were substituted for the use of coal for motive power, 
smelting, heating and lighting buildings, that a saving of some- 
thing like £*400,000 a year might be anticipated for that town. 
During the leCture eledtric lights, fed from a distance, were used. 
The current from a dynamo-machine at the works of Messrs. 
Walker and Hall, a considerable distance from the leCture-room, 
also set in motion an eleCtro-motor on the platform. This in turn 
caused another dynamo-machine to rotate rapidly and produce a 
current with which the leCturer gilded a piece of plate. It was 
also shown that the Sheffield Water Company had a considerable 
surplus supply of water which could be used for producing motive 
power ; and as an illustration of such a use of the water-power, 
a 2-inch board was sawn on the platform by a circular saw driven 
by an eledtric current generated by a water-engine in the yard of 
the Waterworks, and conveyed to the hall by wires crossing the 
streets. In referring to the fact that eledtricity can produce not 
only motive power, but also light and heat, Prof. Ayrton said that 
Dr. Siemens had been able to effedt a saving of about 30s. an 
hour, at the Royal Albert Hall, by replacing the old gas jets by 
eleclric lamps. The science of hanging a brilliant light high up 
had been luckily allowed to ride over the precedent of putting a 
number of feeble glimmers all over the building. 
