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POPULAR SCIENCE REVIEW. 
the electric light last fall as an entirely new subject of experiment, and 
allowed himself to believe that he saw a way to make the light useful which 
others had never thought of ; but when he reached the Patent Office he dis- 
covered that very nearly every idea which he had embodied in his applications 
had either been covered by the patents of other inventors or was not patent- 
able at all. This information is obtained from the Patent Office, and is one 
explanation of the discouragement which reigns at Menlo Park. There is no 
doubt that the Edison light would be a delightful resource for the illumina- 
tion of dwellings, if it could be depended upon. It floods a room as though 
with golden sunlight — pure, brilliant, and mellow. But the inventor has 
never yet been able to regulate his current so as to keep his lamps burning for 
any length of time, and he has never ventured on a single public exhibition of 
it. The public have never seen so much as one of his lights yet. A favoured 
few who have been admitted to his laboratory at Menlo Park have beheld it — 
a single lamp, enclosed in a glass globe, beautiful as the light of the morning 
star. But he has refused to let anyone inspect it closely, and has never 
allowed the exhibition of it privately to last long. He has never been able to 
depend upon its durability. His apparatus is as far from perfection as it ever 
was ; and, in fact, well-informed electricians in New York do not now believe 
that Mr. Edis®n is even on the right line of experiment. 
EXPLANATION OF PLATE Y. 
Fig. 1. Dynamo-electric machine, worked by means of a tuning-fork. 
„ 2. Upper portion of the lamp, showing, a, the spiral of platinum con- 
nected with the terminals, b and c, and enclosing It, the metal rod, 
which by expansion diverts the current, and prevents fusion of the 
incandescent wire. 
„ 3. Detached figure of the shunting apparatus. 
