Popular Science Lectures. 443 
7. — ' ELECTRICITY AT WORK. 
Delivered on Thursday, November 2gth, by Samuel Vyle, Government 
Electrician. 
The lecturer remarked at the outset that whilst the 
ancients knew that rubbed amber would attract light 
substances, and that the merits of the loadstone were 
known long ago, - yet down to VOLTA'S time, the world 
was without the knowledge of what might be termed 
" controllable" electricity. The fact afterwards became 
known that a current of electricity passed through a 
wire, affected a magnetic needle close to it. Then 
Arago and Davy discovered how to magnetise iron 
and steel, which resulted in the electro-magnet by which 
the majority of the telegraphs of the world are worked 
to-day. Soft iron under the influence of an electric 
current became magnetised, but the property was lost 
with the cessation of the current, and it was this fact that 
was utilised in telegraphic work. Very different was 
the action of the current upon steel — it would not 
" let go" but retained the magnetism. The Morse 
Instrument was then described, and also the single needle, 
so much in use upon the British Railways. Reference 
was then made to telephone work generally ; and, under 
the head of electric lighting, a description of the working 
of a dynamo was given. The principles of arc lighting 
and the incandescent lamps were then briefly pointed 
out, and it was stated that from experience of the labour 
at command on estates in the colony, arc lighting was 
not to be recommended for buildings, as these required 
care and skill daily, beyond the ordinary character ; 
whereas the incandescent lamps burnt as long as the 
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