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IT needs but a casual glance to see that Mars is now the brightest object in the evening skies, it needs hut a few evenings watch, even for anyone not acquainted with the stars, to note that Mars is a wandering star as the Greeks called it, a planet. By making a diagram giving the position of Mars with respect to the neighboring stars, it will be easily seen, after a few nights watching, that Mars is now moving toward the west among the stars. The first week in December found Mars due south of the Pleiades and but a few degrees away from tliem. It continues to move west only until the 29th of December, when it ceases its westward motion, becomes stationary, and then moves east at first slowly, and then with increasing pace. To the west of Mars is Saturn, the wonderful, a never-ending source of pleasure to the amateur with his small telescope. It, too, is changing its position among the stars, but with a statelier mien owing to its increased distance from us. Saturn, too, at the present time, is moving toward the west, but it keeps on moving west until after the middle of January, 1912, when it becomes stationary, and then moves also to the east. .The amateur who likes to watch the sky will find a great deal of profit from noting the motions of these two planets' relation to the stars. The accompanying diagram shows the motion of Mars from June 1st to March 31st, and that of Saturn for the same interval, from the first of January to the end of March. A glance will show that Mars “retrograded,” or moved to the west from October 17th to December 19th, while Saturn moved backward on its path for a longer time, hut through less angle, from lOll, September 2nd. to 1912, January 16th. Another glance will show that Mars has three times passed by the Pleiades: first, at the end of August, when it was six degrees to the south of them; for the second time during the first week in December. Toward the end of January will occur the closest of all three approaches, when it again passes to the south. By following the diagram backwards, it will be seen that on August 15th, Mars and Saturn were very close together. As a matter of fact on August 16th at 11 P. M., Mars and Saturn were separated by only twenty-one minutes of arc, which is an angle equal to two-thirds of the moon's diameter, Mars being north of Saturn. On the same night, a few hours later, the moon was in the same part of the sky, passing to the north but four degrees away. This interesting conjunction has been magnificently portrayed by the accompanying photograph taken with the six-inch Bruce telescope by Prof. E. E. Barnard of the Yerkes Observatory. This was taken on the morning of August 17th at 3 :14 o'clock with an exposure lasting twenty seconds. It is a remarkable photograph in that it shows the dark portion of the moon in the last quarter illuminated by “earth shine.” The planet nearest the moon is Mars. After the date of this photograph, Mars was moving rapidly eastward while Saturn soon slowed down and then moved westward. By October 17th, the planets were separated by 25 degrees, when the change in the motion of Mars again began to lessen the distance. They will be nearest each other about New Year's, after which the eastward motion of Mars will again cause the distance to increase. As everyone knows, the apparent motion of the planets is caused by the motion of the planet about the sun combined with that of the earth. The relative motion of Mars, for instance, may be correctly represented by supposing that it has two motions, one its own motion, and superposed on this another, equal in magnitude to that of the earth's motion about the sun, but in the opposite direction. This simple fact explained in detail in every text book on astronomy need not further be elaborated here. A Type of High-intensity Primary Cell By Dr. Alfred Gradenwitz. ANEW high-intensity primary cell invented by H. D. P. Huizer of The Hague owes its high efficiency mainly to the fact that the carbon and zinc are located as closely to each other as possible, the carbon having a grooved surface through which the ions can be discharged easily and rapidly. Wherever these ions after their discharge result in polarization, the apparatus is so designed as to produce immediate depolarization by chemical and mechanical effects, so that the ions coming afterward may be free to discharge on the poles. The high current density and short distance between the carbon and zinc also warrants a uniform and economical dissolution of the metal. At a recent test the electromotive force in open circuit was found to be about 1.95. volts and the working tension with weak currents (up to 1 ampere [0.065 per square inch] per square decimeter electrode surface) about 1.8 volts, with high-intensity currents (up to 5 amperes [0.32] per square inch) about 1.6 volts and with maximum current densities (up to 0.65 amperes per square inch) about 1.4 volts. Current rushes and even short-circuits (up to about 2 amperes per square inch) with tensions reduced in proportion, were found to exert no objectionable action on the cell; the internal resistance was very low (down to 0.01 ohm). Ten incandescent lamps of a total of 26-27 candle-power could be fed permanently with a single cell. The consumption of zinc with diluted sulphuric acid was found to be 1.7 grammes per ampere-hour (the theoretical electro-chemical equivalent being, of course, 1.22 grammes per ampere-hour). The useful current effect was found to be 70 per cent, so that 1 kilogramme of zinc (and 1% kilogrammes of sulphuric acid) will be amply sufficient to develop 1 horse-power-hour, the current expenses only being about 16 cents, viz., 1/10 of that of ordinary primary cells. The depolarizing capacity is so remarkable that one-fourth minute suffices for the cell to recover its maximum tension after a short-circuit. It will be readily understood that these results constitute a remarkable advance over primary cells so far in general use. While the output . of common stationary storage battery cells for each kilogramme of their own weight is 10-15 watt-hours and that of the portable accumulators 25-30 watt-hours, the new cells allow outputs of 30-50 and those designed for transportation operation as much as 100 watt-hours. In connection with a special type of cell the inventor is even able to insure 200 watt-hours for each kilogramme of cell weight. In a test of an electric vehicle equipped with the new cells the current expenses worked out at about 3 cents per ton mile. With a single supply of zincs (about 330 pounds) and several re-fillings of acid, the vehicle covered a distance equal to that between the Hague and Paris (about 300 miles) at an average speed of 18 miles per hour. The new cell would moreover seem to lend itself to the propulsion of electric cars and airships. The new cell is made in two different types. In connection with the tests described above concentric cylinders were used. However, in order even further to reduce the consumption of zinc, a special type of “parallel” cell has been designed in which the carbon surface is likewise increased to a maximum by ribs, though not in the shape of cylinders but of flat plates. The zinc, so far from constituting a homogeneous mass, assumes the form of minute disks performing an automatic motion by which their distance from the carbon is kept constant, insuring a uniform wear.
