MINE SAFETY DEVICES MANNING. 539 



the light better than flame safety lamps, and thus the miner obtains 

 the added safety attendant upon good illumination. 



The bureau's method of procedure is to examine and test lamps 

 submitted to it and to issue approval labels to such lamps as meet 

 the requirements prescribed by the bureau as a minimum standard. 

 Seven types of electric lamps have thus been approved. 



When the work was first undertaken there were few portable elec- 

 tric lamps in use in mines and these were not entirely satisfactory. 

 At the present time there are between 75,000 and 100,000 portable 

 electric lamps in use in the mines of this country, and the lamps 

 approved by the bureau are being adopted at an average rate of about 

 2,000 per week. 



Several years ago the bureau approved the first explosion-proof 

 electric motor. These motors are designed to prevent any explosion 

 or flash within the motor casing from igniting gas in the mine air sur- 

 rounding the motor. The type of motor brought out by the bureau's 

 approval was not only permissible for use in gaseous mines, but rep- 

 resented a standard of construction considerably superior to anything 

 previously in use. One other motor has recently received the bureau's 

 approval. These motors have met with considerable favor and at 

 the present time are being adopted at the rate of about 1,000 a year. 

 The bureau has applications for the test of 16 other machines, the 

 development of which is being carried on by the manufacturers as 

 rapidly as the present congested condition of their factories will 

 permit. 



For the past two years engineers of the bureau have been develop- 

 ing a set of suggested safety rules for the installation and use of 

 electrical equipment in bituminous coal mines. These rules which are 

 now in course of publication, were developed in cooperation with 

 outside mining engineers and mine operators, and are the result 

 of many conferences and revisions. No practical requirement has 

 been omitted that will make safer the installation and use of elec- 

 tricity in mines, and it is therefore believed that the adoption of the 

 rules will greatly further the cause of safety. 



The approval system of the bureau is to be extended to the me- 

 chanical equipment of mines when the laboratory facilities now being 

 provided are completed. 



GASOLINE LOCOMOTRTIS FOR MINES. 



To determine the conditions under which gasoline locomotives 

 might be used in mines without detriment to the health of miners an 

 investigation was made of the maximum amount of carbon monoxide 

 which may be produced by gasoline engines. This maximum amount 

 determines the desirable size and the manner of use of such locomo- 

 tives in a mine and the amount of ventilation necessary. 



