FIRE TESTS IN NEW YORK SUBWAY. The Interborough Rapid Transit company is making a series of tests in regard to the possibility of fire in the subway through the electric current and insufficient insulation. The recent fires there have been caused by these tests, and thus served the purpose of revealing the spots that need safeguarding. Perhaps, the severest of these tests is known as the cable test. It consists of sending high alternating currents through the cable for the period of an hour. If the cable stands this test, it will stand the ordinary currents forever, say the electrical engineers. The same current which tests the cables proves the efficiency of the entire electrical system from the pcfwer house to the third rail, including the insulation.