294 



SCIENCE 



[N. S. Vol. XXXII. No. 818 



power plant of the university. These cur- 

 rents are utilized for lighting or for power, 

 or are transformed by motor-generator 

 sets into direct currents for battery charg- 

 ing and for any other work requiring 

 direct currents. 



The storage battery equipment consists 

 of four batteries of 60 cells each, two hav- 

 ing a capacity of 320 ampere hours each, 

 and the other two a capacity of 120 am- 

 pere hours each. One of the two larger 

 batteries is connected permanently in 

 series. It is the general working battery 

 and carries the direct-current load of the 

 building. The other of the larger batter- 

 ies is broken up into 12-volt units, 6 cells 

 in series. These 12-volt sets may be 

 joined in series, or in parallel, or in any 

 series-parallel grouping. 



The individual cells of the two smaller 

 batteries, called the research batteries, are 

 connected separately to the switchboard. 

 They may all be thrown into series, into 

 parallel or into any series-parallel ar- 

 rangement. This arrangement of batteries 

 permits one to obtain, for example, 2 volts 

 with a current capacity of 7,200 amperes, 

 or 12 volts with a current capacity of 

 2,800 amperes, or 660 volts with a current 

 of 60 amperes. Any other values of voltage 

 and current between these limiting values, 

 may be obtained. 



All currents are distributed from the 

 main .switchboard. At least four conduct- 

 ors run from this board to each room 

 separately, to insure to that room elec- 

 trical service free from variation of volt- 

 age and free from interruption. While, of 

 course, the very heavy currents mentioned 

 above may not be transmitted by the gen- 

 eral wiring of the system, any of the volt- 

 ages indicated can be made available in 

 any research room, lecture room or labora- 

 tory, with current up to 50 amperes. 

 Alternating currents in one- or two- 



phase and at a voltage of 110, 220, 1,100 

 or 2,200 volts can be supplied as desired, 

 and by the interconnection of the phase 

 changers of the department of electrical 

 engineering, polyphase currents of differ- 

 ent epochs and voltages can be thrown 

 upon any line. 



An automatic telephone system with 

 sixteen instruments connects the various 

 central points of the building. And an 

 interconnecting signal system renders it 

 possible to establish, by a few contacts on, 

 at most, two panels, private lines between 

 one room and any other four rooms in the 

 laboratory. These circuits are suited for 

 low voltages only, but have been of the 

 greatest convenience in providing connec- 

 tions for the Callender recorder, for time 

 signaling and for private signal systems. 



The motor load amounts to somewhat 

 more than 85 horse-power. This equip- 

 ment is required for ventilation, elevators, 

 pumps, compressors and the running of 

 the machine shops. 



The following equipment of a research 

 room is typical of all. In addition to the 

 general means for lighting, heating and 

 ventilating, water, compressed air, vac- 

 uum, seven gas outlets, four wall plugs 

 supplying 110 volts direct current and 

 four supplying 110 volts alternating cur- 

 rents are installed. The special- experi- 

 mental circuits just mentioned above run 

 from the main switchboard to each room, 

 and the special signal circuits come into 

 each room. Finally, a special lighting 

 circuit is run in a wooden moulding on 

 the ceiling, 18 inches from the side waUs, 

 to enable a lamp and cord to be dropped 

 at any point over the wall tables for the 

 illumination of galvanometers, telescopes 

 and similar apparatus. 



The working libraries of the two de- 

 partments are installed in a large room on 

 the main floor. The scientific library of 



