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196 THE PHOTOGRAPHIC NEWS. LMARCI 30, 1883. thought should convince that, however well it may be written up for marketing shares, it cannot be more than a laboratory success, a phenomenon of science, a feat of mind over matter. Again, even as a luxury, it would be a nuisance, for the fumes given off from powerful batteries would ruin all substances— metallic or fibrous—that they come in contact with. Thus it is only fair to the investor to say that, when such schemes are offered, caution is a necessity, or they may think too late. But when we produce this great and subtle force—electricity—by mechanical agency, the means used to evolve or give it out show no wearing away of the magnets, no lessening the size of the induction coils, even after producing what would represent millions of candle power; the machine does not lose its properties for producing electricity if due force is given to put the machine in motion at the desired speed. Electricity ! What is it ? No man has yet defined it; no man knows its component parts. It and music may fairly be said to be the twin powers of the air we breathe, for the power of music is capable of enormous range, as electricity is of enormous strength, both of which are actuated by the air, for neither are capable of being produced in vacuo. To the best expert, electricity is a something inexplicable. Theories have been formed by the hundred, and with what success? Merely to open up room for more theory. Butthat electricity pervades all apace where air has free access, is proved beyond doubt; and in no instance is it more palpable than in the fact of it giving forth the feeble spark, as it does the mass of light that equals the brightest day. As a twin power of the air, it may be the strength or actinism of the light the photographer so much depends upon to fix the picture in his camera. The effect of air and light is proved by their influence upon metallic bodies. As a fact, the magneto machine can produce the electric light at any altitude it ma y be—on the mountain top, or down the deepest mine; it may be in a space only capable of holding it in its place ; or it may be out in the open. Its power to produce is regulated by the velocity of motion given to it, and not the space afforded it, and yet the surrounding air does not alter its properties in any way to affect us personally. How like music 1 The violinist may play in the most confined space, and his instrument give out the same note as if he were playing on the wildest moorland; 500 violinists might play in the same way, and 500 other instruments, differing in sound, as violin, harp, dulcimer, trombone, trumpet, bassoon, and the voice (most wonderful of all) giving forth their distinct sounds ; only by the loudness should we be affected, by the deafening sound. It would not affect the air we breathe, wild as the commotion may be, either in discord or harmony. The same by magneto machines ; they might be placed as close together as machinery would work them, and produce a strength that would vie with the lightning’s flash—capable of destroying life or overturning property—and yet we should not be sensibly affected by the electricity thus evolved by the machines in motion ; it would not affect the air we breathe, though the whirl of the machines might be un pleasant to our sense of hearing. Hence I feel I am justified in my idea as to music and electricity being the twin powers of the air, which no man has yet defined. Music can be measured by the vibration to the given chord to denote the sound it will produce, but why produced is beyond explanation. Electricity has been measured infinitesimally, and is seen in the strength put forth by the storm ; but the subtlety defies us to fathom its mystery. This is sufficient to make us wonder. Chemically, we see results, but can turn to the battery cell to see causes and effects, to lead to the result shown. But when mechanical agency is used, we see no diminution in size or weight ; these are facts sufficient to make men wonder at the power and extent of this invisible agency. No better definition can be found than the Genie appearing out of the small jar to the Calendar [yide Arabian Nights Tales). The air—that mysterious agency—has been bisected by man, and its component parts known fractionally. Light—prismatic- ally each ray has been measured, and by demonstrations the power, strength, and property of each ray tested to produce effect. This is seen by the decomposing action of light on metals ; the actinism of the ray applicable to photography; the polarization of iron and other phenomena resulting certain in action by cause and effect. Man can evolve electricity and make it subservient to his will. But no man has yet ventured to assert that he knows the component parts of its subtlety. Man’s knowledge extends to results, as facts of attraction and re pulsion positive and negative actions; there man’s knowledge ceases, then comes the cloud, and heavy and laborious calculations are gone into. To show what ? That figures will not give the causes to lead to the definition of what the wondrous and all prevailing force electricity is. There are some who have aired their assumed knowledge on platforms, and said they knew all about it, &c. The great Faraday, after forty years of study (such as the world knows he gave to the subject of electric science), confessed he knew not of its form, shape, or substance. PHOTO-LITHOGRAPHY AND PHOTO ZINCOGRAPHY. BY MAJOR J. WATERHOUSE, B.S.C., Assistant Surveyor-General of India. CHAPTER VIII.— InKtNG-UP Methods. In these methods the print is first wetted with cold water, and then laid evenly down, face upwards, upon a smooth surface, and transfer ink is applied with a roller or dabber, something in the same way as in the methods last described ; but instead of the ink taking all over the print, it will only attach itself to the lines, while the whites remain clear, or nearly so. Many different modes of doing this have been published from time to time, but the following are some of the best, and will be sufficient to give a good general idea of the operations. Captain Abney inks up prints produced on his “ papyro- type ” paper, described in the last chapter, by drawing them through cold water, and then squeegeeing them down on to a smooth zinc or pewter plate. If necessary, the edges may be secured with strips of paper and india-rubber solution. The superfluous water is then blotted off, and the print rolled in by means of a gelatine roller* charged with ink composed of Best chalk litho, printing ink ... 4 parts Palm oil ... ... ... ... 1 part The roller is at first well charged with ink, and rolled slowly and with some pressure until the print is well charged all over. The roller is freed from the excess of ink by rolling on a clean slab or piece of paper, and then worked smartly and lightly over the print until all inky scum is removed, and the image stands out clear and sharp. Should the sur face of the print become dry and not clear readily, a wet sponge may be passed over it. If the operation be properly performed, a very delicate transfer print is the result. The slight washing given to the print in the first instance is sufficient to remove the bichromate from the paper, and when the transfer print is judged to be properly inked, it is dried without a final rinsing in water, and exposed to light so as to make the whole surface insoluble, and thus prevent it sticking to the stone or zinc when transferred, though it will be sufficiently adherent to prevent slipping. The gela tine surface, being insoluble and hardened, will have no tendency to squeeze out and blur the lines. A somewhat similar process is used at the Military Geographical Insti tute in Vienna, the roller used being of the same shape as the ordinary lithographic roller, but covered with velvet instead of leather. According to Captain Volkmer’s pamphlet, describing the processes in use at the Institute, the operations are as follow. The print, made on the paper described in the last chapter, is taken into a dark room and soaked in a bath of cold water till it is quite limp. It is then laid down on a glass plate, gelatine side up, and the superfluous water removed with blotting-paper. Should the gelatine swell up too much, so that the finer lines take the ink with difficulty, the print may be soaked first for one or two minutes in a bath of bichromate of potash about 1 to 200. * A very gcod composition for these rollers is Gelatine 30 parts Glycerine 22 " Castor oil ® » Water 30 ”