December 21, 1888.] 



SCIENCE 



303 



familiar as the liorse-car now is. In this system tlie conductors are 

 necessarily bared throughout their entire length, and must be pro- 

 tected both for the safety and convenience of the public and also to 

 prevent injury to the conductors themselves. These requirements 

 are fully satisfied by the underground conduit, which promises to 

 be an indispensable element upon all urban lines. 



ten inches in width, consisting of iron yokes set up from three to 

 five feet apart, and slot steels bolted thereto, leaving an opening at 

 the surface of the street of only about five-eighths of an inch. The 

 direct and return supply conductors, consisting of copper bars 

 united by e.xpansion joints, are supported by suitable insulators ir» 

 the upper part of the conduit, where they are out of the way of any 

 slush and dirt which may collect therein. These conductors are 

 placed opposite each other, and are connected in circuit with the 

 dynamos at the central station. The car carries a plough or con- 

 tact device, which extends down through the slot into the conduit, 

 and has two contact-shoes insulated from each other, which rub 

 against the two line-conductors. Flexible conductors in circuit 

 with the two shoes extend up to the car, and are in circuit with the 

 terminals of the propelling motor ; so that, as the car travels along 

 the track, the two housed conductors are constantly connected', 

 through a travelling loop circuit supplying the motor with current. 

 The shank of the plough is narrower than the slot, and the con- 

 tact-shoes can be folded into line therewith, so that the entire 

 plough can be inserted or moved from the conduit at will ; and ac- 

 cidental breaking of the plough is guarded against by providing a 

 spring catch normally holding the plough in place, but adapted to- 

 give way should any accidental obstruction be struck. In order to 

 compensate for any cur\'es or irregularities in the line of the slot, a 

 transverse guide is provided upon the vehicle, and a traveller at the 

 upper end of the plough moves freely along this guide, while swiv- 

 elling or other jointed connections may be employed when found 

 desirable. The car is propelled by either one or two motors of 

 about fifteen horse-power, which are generally placed underneath 

 the car-body, and centred around the axles, to which they are con- 

 nected through intermediate speed-reducing gearing. The usual 

 brakes are provided for stopping the car, while circuit switches and 

 resistances control the speed and power of the motors with all the- 

 precision and nicety of which steam-motors are capable. 



From this description the essential features of construction in 

 the conduit system, as well as the mode of their operation, will be 

 readily understood, but many questions touching upon the practi- 

 cal working of the system will suggest themselves to those inter- 

 ested in it as a commercial enterprise : Will the conduit become 

 filled with dirt or with snow .' Can the necessary insulation of the 

 underground wires be maintained ? Will the car have sufficient 

 traction? What will happen if the car runs off the track ? All these 

 objections have been anticipated, and it is found that the satisfactory 

 operation of the conduit road built by the Bentley-Knight Com- 

 pany at Allegheny City, Penn., demonstrates that they are ground- 

 less. This road, which is known as the Observator)- Hill Passenger 

 Railway, is about four miles in length, the conduit being employed 

 for about one-fourth of this distance, and it has been in continuous 

 operation since the first day of January, iS88. There are thirty- 

 four cur\'es on the line, not including turnouts and switches. The 

 maximum grade is 9fJ feet in loo feet, on a length of 400 feet, and 

 this is on a reversed curve (radii 100 and 200 feet). The sharpest 

 curve has a forty-foot radius on five-per-cent grade. Greater 

 natural difficulties than these can scarcely be found on any street- 

 railway in existence, and hence the successful working of the road 

 during the severe snows and ice of the last winter is perhaps the 

 best guaranty of the practicability of the system. Other conduit- 

 roads are now under process of construction by the same company, 

 noticeable among which are one of over three miles in length, con- 

 tracted for by the West End Railway Company of Boston, and the 

 Fulton Street Road of New York City. The progress of these - 

 roads will be watched with interest. 



That for the West End Company in Boston is just completed,'. 

 and will be put into operation in a few weeks, and thoroughly 

 tested. 



This system has been developed by the Bentley-Knight Electric 

 Railway Company of New York City, who claim to control by pat- 

 ented rights all practicable methods of locating the supply conduc- 

 tors in a conduit, and who, however this may be, have built the 

 only roads operating on this plan. Either between or outside of 

 the track-rails is laid a conduit about fifteen inches in depth and 



PHILOSOPHY AND SPECIALTIES. 



On Saturday evening. Dec. S. the annual address of the retirfng' 

 president of the Philosophical Society of Washington, Col. Garrick 

 Mailer)', U.S.A.. was delivered before a ven,- large audience, com- 

 posed not only of the members of the Philosophical Society, but of 

 those of the Anthropological. Biological, Chemical, Geographic, and 

 Woman's Anthropological Societies, whose attendance had beea 



