Fig. 2 represents a device especially designed as a parlor ornament.  When the plant is touched, the insects resting upon it immediately begin to flap their wings as if they desired to fly away.  These insects are actuated by a Leclanche pile hidden in the pot that contains the plant.  The insect itself is nothing else than a mechanism analogous to that of an ordinary vibrating bell.  The body forms the core of a straight electro-magnet, c, which is bent at right angles at its upper part, and in front of which is placed a small iron disk, b, forming the animal’s head.  This head is fixed upon a spring, like the armature of ordinary bells, and causes the wings to move to and fro when it is successively attracted and freed by the electro-magnet.  The current is interrupted by means of a small vibrating device whose mode of operation may be easily understood by glancing at the section in Fig. 2.  The current enters the electro-magnet through a fine copper wire hidden in the leaves and connected with the positive pole of the pile.  The negative pole is connected with the bottom of the pot.  The wire from the vibrator of each insect reaches the bottom of the flower-pot, but does not touch it.  A drop of mercury occupies the bottom of the pot, where it is free to move about.  It results that if the pot be taken into the hand, the exceedingly mobile mercury will roll over the bottom and close the circuit successively on the different insects, and keep them in motion until the pot has been put down and the drop of mercury has become immovable.

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PORTABLE ELECTRIC SAFETY LAMPS.

One of the most difficult problems that daily presents itself in large cities is how to proceed without danger in the search for leakages in gas mains, or in attempts to save life in houses accidentally filled with explosive gases.  The introduction of a flame into such places leads in the majority of cases to accidents whose consequences cannot be estimated.  The reader will remember especially the explosion which occurred some time ago in St. Denis Street, Paris, and which killed a considerable number of persons.  It has, therefore, been but natural to think of the use of electricity, which gives a bright line without a flame, in order to allow life-saving corps and firemen to enter buildings filled with an explosive mixture, without any risk whatever.

[Illustration:  FIG. 1.—­ELEVATION (Scale 1/25).]

Several electricians have proposed ingenious portable apparatus for this purpose, and, among these, Mr. A. Gerard, whose device we illustrate herewith.  In this system the electric generator is stationary, and remains outside the building.  This, along with all the rest of the apparatus, is mounted upon a carriage.  The operator, instead of carrying a pile to feed the lamp, drags after him a very elastic cable containing the two conductors.  This “Ariadne’s thread” easily follows all sinuosities, and adapts itself to all circumvolutions.  The entire apparatus, being mounted upon a carriage, can be easily drawn to the place of accident like a fire engine.