70
" Available work on driving shaft, 62 h. p. Electrical work on generator 53.59 " Difference absorbed 8.51 " Work absorbed by armature 2.33 "
2. _Line:_ Work absorbed by conductors 7.21 h. p.
3. _Receiving dynamos_: Speed of shaft 248 revolutions. Electromotive force at terminals 4508 volts. Electromotive force total 4242.67 " Electrical work of receiver 41.44 h. p. Work measured on receiver shaft 35.8 " Difference absorbed 5.64 " Duty obtained, not including exciting machine 57 per cent. Duty obtained, including exciting machine 48 "
During the various experiments the current traversing the line varied from 7.59 amperes to 7.21 amperes. No heating of any kind was observed.
M.J. Bertrand, who communicated a paper to the Academy of Sciences on the subject, commented on the relatively low speeds. It corresponds to a linear displacement of the surface armatures, in no case exceeding the speed of a locomotive wheel. The tension reached 5,500 volts., under very satisfactory mechanical conditions, and with a current that in no way endangered the line. This first experiment is certainly encouraging, and it will be followed by others of a more complete and exhaustive character. MM. De Rothschild are now embodying a powerful commission of French and foreign scientists who will follow the subject carefully, and report upon it. It may be safely predicted that one result of this action will be the development of a new series of observations of the highest technical interest and value.--_Engineering._
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THE LOCKED AND CORDED BOX TRICK.
The trick with the locked and corded box, I believe, is an old one, though perhaps not in its present form. In late years it has been revived with improvements, and popularized by those clever illusionists, Messrs. Maskelyne & Cook and Dr. Lynn, at the Egyptian Hall. There are several ways of working the trick or, rather, of arranging the special bit of mechanism wherein the peculiar features of the box consist. The one I am about to de