Longitudinal Sleepers. To the Editor of the SCIENTIFIC AMERICAN: Referring to the remarks of T. C. L. regarding “Longitudinal Sleepers,” I would state that we do not have to go to England for an example. I recollect the construction of what was known as the Ohio Penn sylvania Railroad, in 1852, west from Pittsburg, Pa. The line is now known as the Pittsburg, Fort Wayne Chicago Railroad. The men employed to grade and lay tracks, etc., were principally Irish, and the earth was moved by one-horse dump carts. The locomotives were designated not by numbers, but by names of the towns and cities through which the lines ran. I re member one of a pair of locomotives built from the same patterns—either the “Alliance” or “Allegheny” —which fell down an embankment just west of Roch ester, Fa., and lay there a week or two till they could grade and track a way to haul it up to the main track. The locomotives burned wood, which was sawed by machines operated by one-horse tread power at stations along the line. But about the track: After carefully grading the earth, there were laid two lines of timbers longitud inally, set apart the width of the track. Over these were laid laterally the ties, such as are now in use. My recollection is that the ties (then called "cross-ties") were laid loosely on the sleepers. To the ties the rails were spiked, their ends being joined by wrought-iron "chairs," notches in the rails and holes in the chairs being provided for the spikes which se cured the joints, which were always placed on ties. I do not know when the sleepers were abandoned on that line, and the ties laid directly on the earth. STANTON WEAVER. Washington, D. C, November 1, 1907. How Science might Force a Spelling Reform. To the Editor of the SCIENTIFIC AMERICAN: In the main operating room of the Postal Telegraph Cable Company, in Chicago, one can see the electric typewriter "quad" between Chicago and New York, also the "octopus" between Chicago and St. Louis. These marvelous instruments both send and receive telegraphic messages moving over the wires in the Morse code. At the sending desk, say in New York, a young woman typist operates the keys of a spe cially constructed typewriter, while at the receiving end, in Chicago, the message is automatically tran scribed in Roman type on the customary form ready for delivery. The electric telegraphic typewriter is suggestive of great possibilities, and, in the mind of a layman, natu rally raises the question: "What insurmountable ob stacle prevents a similar attachment to the tele phone?" Would it be any more astonishing than other recent discoveries in electricity? One must admit that the fundamental principles of the telegraph and tele phone are widely different. At the same time, in a purely phonetic language like the Spanish, one has for each letter a fixed, standard unit of sound with which to deal. German, also, is relatively phonetic as com pared to English. When we come to the latter, our mother tongue, however, we realize that such an in strument, if ever invented, could never transcribe into the word "knowledge" the sounds "n-o-l-e-j." There fore, the Anglo-Saxon commercial world would at once demand a phonetic alphabet, if it should be thus offered by science. No business house could resist the temptation to purchase an "automatic stenographer," always ready and infallibly correct. E. F. MCPIKE. Chicago, 111., October 21, 1907. -? ?- The Aero Cluh Kxliibit. To the Editor of the SCIENTIFIC AMERICAN: The aeronautical exhibit given in connection with the New York Automobile Show is well calculated to amuse the people more by its absurdity than impress them with the practicability of the machines exhibited; and indeed when one listens to the comments which it evokes and observes the jocular attitude with which most spectators approach this part of the inclosure, and the broad smile of easy good-natured tolerance with which they view the various devices purporting to sail on the air, it is evident that it fulfills the purpose of entertainer most admirably. To those not deeply interested, it must surely be a great relief to come here after being oppressed and confused with the massiveness and astonishingly intricate mechanism of the automobile, and relieve their tired brains by gazing on the curious display of crude, trivial, and inconse quent material with which it is proposed to compass flight. When we consider the costly machinery, ma terial, and workmanship it requires to turn out an ordinary bicycle or motorcycle, to say nothing of the auto and motor boat, and on the other hand are obliged to witness the efforts of misguided inventors, with little or no exact knowledge in the premises, attempt ing to solve with a few bamboo sticks, some canvas, and an inadequate motor, that which in reality re. quires the most subtle and elaborate calculations to determine the most efficient type, and the finest and most costly material in its construction, the sublime folly of the thing is at once apparent. I would like to speak at greater length, but I do not wish to encroach unnecessarily on valuable space. Of what use is it to point out the obvious deficiencies that exist when the deductions, experiments, and conclusions of able in vestigators better qualified to teach this science pass unheeded? I will make but one suggestion: when an inventor conceives an idea, let him look up such au thorities as O. Chanute's "Progress in Flying," or "Con ference on Aerial Navigation"; he will probably learn of some similar machine that has been tried and found wanting; and unless he is desirous of gaining sudden glory and possible gain as the inventor of a flying machine that signally fails to exhibit that desirable quality, he will sheer off on another tack. I would particularly recommend a careful reading of the essay in the latter work, "On the Problem of Aerial Naviga tion," by the late C. W. Hastings, a promising young civil engineer, whose untimely death must ever remain a source of regret to all who are interested in the advancement of the science. J. C. PRESS. South Nor walk, Conn. -?. ,.?- An Optical Illusion Produced by an Ingenious Arrangement of Straight Lines. To the Editor of the SCIENTIFIC AMERICAN: Herewith I send what I believe to be an optical illusion. I have never seen the same before, having come upon it by accident, but have never yet found any one who did not pronounce line CD longer than line A B. If this is of any use to you, you are wel come to it. G. W. HINMAN. [We call attention to the optical illusion illustrated below in which both lines are of the same length, although A ? seems to be much the shorter. The principle is obviously the same as that to which our correspondent calls attention. Both illusions depend for their efficacy on the fact that divergent lines give the appearance of length to a straight line with which they are associated.—ED.] The Sterilizing Effect of Saliva. To the Editor of the SCIENTIFIC AMERICAN: Nowadays in deference to public opinion we dentists are all sterilizing our dental instruments, whereas formerly we simply gave them such cleansing as com mon decency properly demanded, and very properly, too. But now it is contended that dental instruments are dangerously infected by the secretions of the mouth, if not by what is popularly called "decay" in cavities which need filling. If this theory is true, why are not people fatally poisoned by the use of teaspoons, forks, cups, and glasses out of which they drink? Why is not the food we eat from plates also poisoned by contact with plates and cups previously used by others and only washed supposedly with soap and hot water, wiped on unsterilized dish towels, and then handled by the unsterilized hands of the cooks and waitresses just be fore we use them? We use all of these unsterilized articles a hundred times, perhaps a thousand times, where a dental instrument enters the mouth once. Why is not the ragamuffin dead in ten minutes after eating parts of a rotten apple or orange which he picked up from the street? Is it not because the fluids and mucous secretions of the mouth, as well as of the nostrils, are far more efficient sterilizers than any man can invent—an in stantaneous sterilizer without being itself dangerous to us to touch or swallow, like the sterilizers we are now using in our practice? We all know the Inner cavities of the body cannot be opened to the air, even, much less safely be oper ated upon with surgical instruments or touched with unsterilized fingers, without great risk of death to the patient, and the success of modern surgery there fore is most marked. But I have practised dentistry for more than fifty years and I never knew or read of a patient being poisoned by ordinary dental opera tions, and I have personally known more thr.n one dentist going from one patient to another without even washing his hands or giving any attention to cleaning his instruments. Of course such negligence is shocking and contemptible. In the winter and spring of 1900-1 I collected about a pint and a half of pure saliva by means of a drain age pipe used in filling operations, and saved it for an experiment, which consisted of exposure to the air during the hottest summer New York has experienced that I know of, viz., 1901. In September that fluid was perfectly limpid and absolutely free from odor or other evidence of decomposition, as Dr. Bellamy of Bellevue Hospital can testify. Is there any other por tion of the human body, except perhaps the hair, nails, and bones, which could have stood that test, and does it not prove that those fluids are themselves wonder ful sterilizers before which bichloride of mercury and sublamine are nowhere? Meanwhile those people who intrust the sterilization of their eating utensils to their cooks and butlers need not fear that their den tists do not sterilize their instruments, for we all do it. October 23, 1907. CHARLES A. NASH. The Current Supplement. The current SUPPLEMENT, NO. 1664, contains an un usual number of interesting technological articles. The process known as case-hardening is described most thoroughly by George Shaw Scott, a recognized Eng lish authority. Octave Chanute presents an excellent consideration of the steaming of timber. The fifth installment of Prof. Watson's "Elements of Electrical Engineering" is published. The installment deals with constant-potential generators. L. H. Flanders traces the trend of storage battery development. Mme. Curie discusses the atomic weight of radium. W. G. Clark writes on helion filaments. The recent work of Prof. Delage in producing what passes for artificial life has attracted some attention in the newspapers. For that reason our Paris correspondent's summary of what he has accomplished is timely. The interest of the scientific world was recently aroused by the story of Prof. Metschnikoff's experiments upon fer mented lactic bodies, which were found to have a highly beneficial action upon the organism. He claims that their use will tend to restore health generally, and even to lengthen life. Hitherto it has been almost impossible to procure these products on a practical scale. How this is done, and what the substances really are, constitute the subject of an article entitled "Kefir and Yohourth." Prof. H. Molisch has recently published the results of several years' study of purple bacteria. A few of his interesting discoveries are briefly described. The "Development of Armored War Vessels," which is the title of J. H. Morrison's review of the rise of the United States navy, passes to a thirteenth installment, in which the more recent bat tleships and cruisers are described and illustrated. In an article entitled "Astronomy on Mont Blanc" the work of Prof. Janssen is described. The Alcohol Congress. A congress of industrial alcohol has been organized by the commission of the Paris Automobile Show this year, and it will be held during the period of the expo sition, which lasts from Nov. 12 to Dec. 1, under the auspices of the Automobile Club of France. The work of the congress is divided into a number of technical and economic sections, which will bring out the most recent information in the field of industrial applica tions, such as to motors for automobiles, stationary engines, lighting and heating, etc. The first section of the technical category is devoted to applications of alcohol to automobiles. Second section, to industrial, agricultural, and commercial applications outside of automobiles. Third section, to lighting and heating. Fourth section, to manufacture, denaturing, and car bureting of alcohol. In the category of economic sec tions of the congress are first, production and consump tion; second, applications, depots, instruction of the public; third, legislation, customs duties, statistics; fourth, use of denatured alcohol in the war and navy departments. The latter section is specially concerned with the question of automobiles and hauling cars for army transport. The two groups of sections will hold separate meetings to discuss these questions. Besides this, it has been decided to hold a full meeting of all the sections in order to consider the fiscal questions relating to denatured alcohol. By rubbing metals with salt, before applying mer cury, the ancients obtained a reaction similar to that for which copper sulphate is used. The chlorine re leased from the salt formed a silver chloride easily at tacked by tne mercury, so as to form an amalgam,.