in and out of action.  There are also several connecting terminals, b b’, l, &c., and a comparison resistance R (figure 98).  A small key K is fixed to the terminal l (figure 99), and used to put the current on the lightning-rod, or take it off at will.  A leather bag A at one side of the wooden case (figure 99) holds a double conductor leading wire, which is used for connecting the magneto-electric machine to the bridge.  On turning the handle of M the current is generated, and on closing the key K it circulates from the terminals of the machine through the bridge and the lightning-rod joined with the latter.  The needle of the galvanometer is deflected by it, until the resistance in the box R is adjusted to balance that in the rod.  When this is so, the galvanometer needle remains at rest.  In this way the resistance of the rod is told, and any change in it noted.  In order to effect the test, it is necessary to have two earth plates, E1 and E2, one (El) that of the rod, and the other (E2) that for connecting to the testing apparatus by the terminal b1 (figure 99).  The whole instrument only weighs about 9 lbs.  In order to test the “earth” alone, a copper wire should be soldered to the rod at a convenient height above the ground, and terminal screws fitted to it, as shown at T (figure 99), so that instead of joining the whole rod in circuit with the apparatus, only that part from T downwards is connected.  The Hon. R. Abercrombie has recently drawn attention to the fact that there are three types of thunderstorm in Great Britain.  The first, or squall thunderstorms, are squalls associated with thunder and lightning.  They form on the sides of primary cyclones.  The second, or commonest thunderstorms, are associated with secondary cyclones, and are rarely accompanied by squalls The third, or line thunderstorms, take the form of narrow bands of rain and thunder—­for example, 100 miles long by 5 to 10 miles broad.  They cross the country rapidly, and nearly broadside on.  These are usually preceded by a violent squall, like that which capsized the Eurydice.

The gloom of January, 1896, with its war and rumours of war, was, at all events, relieved by a single bright spot.  Electricity has surprised the world with a new marvel, which confirms her title to be regarded as the most miraculous of all the sciences.  Within the past twenty years she has given us the telephone of Bell, enabling London to speak with Paris, and Chicago with New York; the microphone of Hughes, which makes the tread of a fly sound like the “tramp of an elephant,” as Lord Kelvin has said; the phonograph of Edison, in which we can hear again the voices of the dead; the electric light which glows without air and underwater, electric heat without fire, electric power without fuel, and a great deal more beside.  To these triumphs we must now add a means of photographing unseen objects, such as the bony skeletons in the living body, and so revealing the invisible.