2IO 



SCIENCE. 



[Vol. XII. No. 300 



that of the grid to be pasted. The grids are passed across the 

 opening by rolls, have their cavities filled with the red lead which 

 is being forced out, and then pass between wheels whose distance 

 apart is equal to their thickness, where they are polished, the grids 

 coming from the machine with their perforations filled with paste 

 of an equal density at every point. The different rolls and wheels, 

 and the screw, are geared together, so that their relative speeds are 

 invariable. 



The method of manufacturing the support plates, or ' grids,' has 

 also been improved upon. The old method was simply to cast 

 them ; and, although the process was a cheap one, yet the plates 

 lacked in strength and density. Mr. Madden has devised a press 

 by which they are formed by hydraulic pressure. Besides the ad- 

 vantages of greater density and homogeneity, giving an improved 

 strength and conductivity, the process allows smaller holes and 

 thinner partitions than can be obtained by casting. 



These improvements in manufacture should result in a greatly 

 reduced cost, and in an increased efficiency and length of life. 

 Storage-batteries are just at the point of becoming economical for 

 many purposes, and a moderate reduction in cost and depreciation 

 will turn the balance. 



New Street-Car Motor of the Sprague Company. — 

 Since the beginning of the year, the Sprague Electric Railway and 

 Motor Company has equipped a number of street-railways with 

 electric-motor cars, some of the installations having been difficult 

 and important. The result of the year's experience has been the 

 adoption of a motor differing considerably in type from that here- 

 tofore used, which has been described in this journal. In the new 

 form a single magnetic circuit is used, as in the Edison dynamos, 

 the axle of the car passing through bearings on the yoke. At the 

 other end the poll-pieces are suspended from a cross-piece on the 

 truck by a heavy spiral spring. Another spring below prevents the 

 motor from rising when the motion of the car reverses. The 

 motion is transmitted from the armature to the wheele-axle by two 

 pairs of gears, — one on each side of the car, — one of the wheels 

 in each case being of fibre to deaden all noise. The reduction is 

 12 to I. There are two commutators on each armature, — one at 

 each end, — with a single brush for each. The object of this is to 

 have all the brushes or\ top, where they can be easily adjusted and 

 inspected. It also decreases the wear. The old form of brush 

 consisted of a number of strips of copper riveted together, and set 

 at a slight angle with the commutator bars. This allowed the 

 direction of rotation to be reversed ; but there was more or less 

 wear, especially when the armature revolved against the brushes. 

 In the new brush a number of thin laminas of copper are strung on 

 a rod in a bevelled holder, and bear almost straight down on the 

 commutator, inclining slightly in the direction of motion. When 

 the machine is reversed, the strips are first carried up to the verti- 

 cal, and then a little past it in the new direction of rotation, until 

 brought up by the inclined sides of the holder. The motors are 

 controlled as formerly, by switches on the two platforms of the car, 

 and the cars are intended to travel in both directions. The whole 

 arrangement is compact, and should be extremely efficient. It is 

 an improvement on the old type of motor, which has been very 

 successfully used. 



Electricity for Tempering Steel. — Electricity has been 

 successfully applied for tempering watch-springs and other forms 

 of spring steel, whether in the form of ribbon or wire. The steel 

 is wound on a spool, whence it passes down through a bath of oil. 

 An electric current is sent through the wire, of such strength as to 

 keep it at the proper redness to answer the desired requirements of 

 temper. As the heating is not done in contact with the air. but is en- 

 tirely beneath the surface of the oil, there is no trouble from blis- 

 tering, as in the ordinary methods. The final temper is drawn in 

 the same manner, and the wire or ribbon is finished by means of 

 rolls. The process is also applied to a number of springs besides 

 those for watches, including piano-wires. In all cases the process 

 can be controlled to a nicety, both as to the exact temper and its 

 uniformity through the wire. 



Standards of Light. — The committee of the British Asso- 

 ciation, of which Prof. Vernon Harcourt is chairman, has submitted 

 a report on comparative tests of standards of light. These tests, 



made on six classes of standards, have been carried on for four 

 years, and as a result the committee recommends the pentane 

 lamps. Ordinary sperm candles vary, because the sperm is not a 

 definite chemical compound ; and the luminosity varies with the 

 composition, and the locality and length of the wick. The flame 

 is also liable to fluctuate. It is difficult to obtain sperm candles 

 perfectly free from oil. Perfectly dry sperm has a comparatively 

 high melting-point, and candles made of such material require a 

 thicker wick ; so that candles of the same size made of this mate- 

 rial give less light than those formerly accepted as standards. The 

 amylacetate lamps are constant, but their reddish light is against 

 them. The pentane standard is reliable : it has no wick, and the 

 light does not alter with slight variations in the specific gravity of 

 the pentane. In a special series of comparative tests as to the 

 merits of the amylacetate lamp, the pentane standard, and the pen- 

 tane lamp, the pentane lamp was found almost as good as the 

 pentane standard. Three observers recorded the results, and 

 changed their positions after each set of simultaneous observations. 

 The pentane lamps differed, in a total of I,ii8 tests, by i per 

 cent in 86 cases, by 2 per cent in 57 cases, by 5 per cent in 19 

 cases, and in a few instances by 10 per cent. Other tests were 

 made to reduce the platinum unit of M. Viole — the light given off 

 by a square centimetre of platinum at its melting-point — to a 

 practical shape. Platinum-foil with a surface of a quarter of a 

 square inch was stretched over rollers and heated to its melting- 

 point, but the results were too variable to be of value. When 

 wound over steel rollers, the heat was conducted away too rapidly. 

 Experiments with platinum fused by the blowpipe were equally un- 

 satisfactory. The heating of a platinum strip by the current of 

 eight or ten accumulators gave better results, but the platinum is 

 apt to buckle. Other lamps and flames were also tried. Carbon 

 filaments waste, nor would the action of photographic rays on sen- 

 sitive-plates lend itself to standard tests. The committee therefore 

 recommends the pentane standard and also the pentane lamp. 



Effect of Electric Currents on Plants. — Prof. E. 

 Wollny of Miinich has experimented on the effect of electric cur- 

 rents of different intensities and characters on the growth of plants. 

 Small plats of about four metres square were provided, and were 

 separated by plates penetrating twenty-five centimetres into the 

 soil. On the two sides of one of these beds, plates of zinc were 

 sunk, the dimensions being thirty centimetres by two metres. 

 They were connected by an insulated wire, with five Meidinger 

 cells in the ciicuit. Another enclosure had an alternating current 

 constantly sent across it, while in a third there were simply buried 

 a copper and zinc plate connected above the earth by an insulated 

 wire. The three enclosures were therefore subjected to different con- 

 ditions, — to a weak direct current, to a comparatively strong direct 

 current, and to an alternating current. Several specimens of grain, 

 potatoes, carrots, etc., were planted, and were subjected to the ac- 

 tion of the currents until they reached maturity. Comparing them 

 with plants grown under ordinary conditions, the result to which 

 Professor Wollny is led is, that electricity, whether under the form 

 of continuous currents of different intensities or of alternating cur- 

 rents, exerts no influence on the vegetation of plants. 



HEALTH MATTERS. 

 Depressed Areas as Health-Resorts. 



Dr. Wj\LTER Lindley of Los Angeles, Cal., contributes to the 

 New York Medical Record an interesting paper on the effect upon 

 invalids and others of compressed air below the sea-level. He 

 says that in the eastern part of San Diego County, about one hun- 

 dred miles from Los Angeles, is a depression traversed by the 

 Southern Pacific Railroad, known to geographers as the San Felipe 

 Sink, but commonly called, on account of the innumerable shells 

 spread over its surface, the Conchilla Valley. This basin is about 

 one hundred and thirty miles in length by thirty miles in average 

 width. The deepest point isabout three hundred and sixty feet 

 below sea-level. 



In this valley live about four hundred of the Cohuilla Indians. 

 This is an interesting tribe. Dr. Stephen Bowers, in a paper read 

 before the Ventura County Society of Natural History, March 5, 



