324 



SCIENCE. 



[Vol. IV., No. 



Bessemer' s telescope never would be completed in 

 the intended manner, and this opinion was evidently 

 shared by many gentlemen present. 



On Tuesday Sir Frederick Bramwell explained 

 the method employed to warm the Third Middlesex- 

 county lunatic-asylum at Banstead, Eng., where a 

 circulation of warm water is produced by centrifugal 

 pumps, which maintain two parallel mains in a rela- 

 tively plus and minus condition. The discussion 

 was a comparison of warm water and steam for heat- 

 ing purposes; and the former was shown to have 

 various advantages over steam, where the expense of 

 the plant is not considered. 



Mr. J. C. Hoadley's paper on driven wells fol- 

 lowed, and was a description of a series of experi- 

 ments to determine the way in which water moves 

 toward a well from which it is pumped. Driven 

 were shown to obey the same law as open wells; 

 which is, that the water simply runs down hill, tow- 

 ard the well, its flow being more or less obstructed 

 by its percolation through the soil, so that its surface 

 forms a slope more or less steep, i.e., an 'obstructed 

 hydraulic slope.' This is only what was to have 

 been expected, but it is interesting to have it proved 

 experimentally. In the discussion, a fresh-water 

 well was instanced, bored on the sea-beach, in which 

 the water rose and fell with the tide ; the weight of 

 the latter depressing the underlying and separating 

 strata. 



Mr. W. A. Traill not being present, Dr. Fitzgerald 

 of Trinity college, Dublin, described the Giants' 

 Causeway and Portrush electric tramway. A work- 

 ing model of the same is to be placed in the electrical 

 exhibition. Water-power is used for this line, which 

 is six miles long, the American turbine used being 

 a mile beyond the end ; so that the maximum distance 

 over which the electricity is carried is seven miles. 

 The rails carry only the return current; there being 

 a third rail, on two-feet-high posts at the side of the 

 track, for the direct current. Two springs rub along 

 on this rail to connect it with the dynamo in the car: 

 these being placed as far apart as possible, an opening 

 less than their distance apart can be passed without 

 breaking the current. The railway, however, runs 

 along a cliff by the sea, so that there are but few 

 openings. The road, though new, is represented as 

 a complete success. The line is quite hilly, the maxi- 

 mum incline being one in twenty-eight; crossing- 

 places are all arranged on an incline, so that the car 

 running down can give up the third rail to the other, 

 and go on by gravity. The electrical arrangements 

 were planned by William Siemens, his death occur- 

 ring just as he had seen the whole thing in success- 

 ful operation. It is interesting to note, that the 

 current itself has been used to telegraph to the next 

 car, ordering it to stop. The current is governed by 

 a man in charge of the turbine, who regulates the 

 water to the work: this reminds us of the suggestion 

 of Professor Thompson at the Montreal meeting, that 

 the fireman should be able to completely regulate an 

 electric-light plant by his firing. Running expenses 

 by horse-power, steam-power, and by the turbines, are 

 found to be in the proportion 10:7:3; so that, where 



water-power can be obtained, an immense saving can 

 be effected by the arrangements here used. Dr. Preece 

 followed, and described Mr. Holroyd Smith's im- 

 provements in electric railways. Mr. Smith employs 

 much the same arrangement as on our cable lines, 

 using, however, in place of the cable, a pair of fixed 

 electrical conductors, between which runs a shuttle; 

 the current is taken off by it, and brought up to the 

 car through the groove, thus placing the electric con- 

 ductors under ground, as they evidently should be. 

 Other minor details were described, otherwise the 

 line is essentially the same as that previously de- 

 scribed. 



Mr. A. Stirling then followed with a paper in 

 which the economy of the electric light was made 

 the subject of calculations based on the author's 

 experience. It was stated, that at present, for light- 

 ing a compact block, the incandescent light could" be 

 considered as no more expensive than gas at $1.69 

 per thousand. Mr. Preece opened the discussion by 

 a criticism on the theoretical character of the calcu- 

 lations given, claiming that no dependence could be 

 placed on such statements, and went on to give his 

 own experience, which, however, appeared to fairly 

 sustain Mr. Stirling's figures. He stated that he 

 had experimentally lighted three miles of streets in 

 London (Wimbledon), and that it was not a success; 

 the turning-point seeming to be the price of gas, $2.25 

 in New-York city, but only one-third that price in 

 London. Mr. Preece described his own establishment, 

 where, by means of a gas-engine in the garden, the 

 house is lighted in the most convenient fashion (in- 

 cluding a doll's house of four rooms). He stated also, 

 that the same quantity of gas gave more light when 

 thus indirectly used, than could be got from it by 

 burning it in the best gas-burners: this is readily to 

 be believed, the gas furnished by gas-companies be- 

 ing much better adapted for producing heat than 

 light. It is to be hoped that the time will soon come 

 when the present gas mains and pipes will be em- 

 ployed to distribute gas for heating-purposes alone. 

 Instances were given where the amount manufac- 

 tured had been increased, or the quality of the goods 

 improved, over ten per cent, by the introduction of 

 ■ electric lighting. Mr. Preece explained the superi- 

 ority of this light, by saying that while in the arc 

 light a candle-power was obtained by the expenditure 

 of but one watt of energy, or by the incandescent 

 light two and a half watts, gas required the equiva- 

 lent of sixty-two, and candles of ninety-seven watts, 

 for every candle-power produced. The great stum- 

 bling-block in universal electric lighting was shown to 

 be the enormous cost of the mains for conveying the 

 electricity over long distances. At the afternoon 

 session, Mr. Crampton exhibited a piece recently cut 

 out in repairing the first submarine cable ever con- 

 structed, and which he laid under the English Chan- 

 nel over thirty years ago. The model was then sent 

 to the historical collection of the electrical exhibition 

 as a donation to the Franklin institute. Mr. J. Dil- 

 lon read two papers describing his method of regu- 

 lating floods and an automatic method of sounding 

 the bottoms of shallow rivers. The first depends on 



