Professor Trowbridge's Exeriments.

Professor John Trowbridge, director of the Jefferson Physical Laboratory, has recently completed an entirely new apparatus for taking X ray photographs. He has prepared the largest storage battery in the world, which consists of 10,000 cells, with a voltage of 20,000, which can be raised to 600,000 by means of an accumulator. This battery will give a flaming discharge in air, three feet in length.

Up to this time photographs have been obtained by Holt's machine, or by the induction coil, but Professor Trowbridge has just taken a photograph with his new apparatus which gives a clearer outline of the bones of the hand than any yet taken. This is the first photograph ever taken by means of a battery.

Till now it has been an open question as to how many volts are required to create the flash of the Crooke's tube. This Professor Trowbridge has settled by means of the new battery. Instead of the 20,000 volts which were before considered necessary, he has found that 100,000 are needed to produce the flash, and that with increasing voltage the picture becomes steadily plainer. This current, acting through one ten-millionth of a second, develops one million horse power.

Another important discovery made by Professor Trowbridge is that the current through the Crooke's tube goes in only one direction and not in both as has been supposed.