Popular Science Monthly/Volume 19/May 1881/Editor's Table
THE PHOTOPHONE IN RESEARCH.
THE elegant research of Professor Tyndall, which we publish in the present number, will well repay the careful attention of our readers. It is of interest, not only on account of the very complete confirmation of results previously obtained by this physicist, but also on account of the novel method employed, and the promise this gives of wide utility. The photophone is barely six months old, but these experiments show that it already has a large field of usefulness before it, and it is, perhaps, not too much to expect that it will prove to be one of the most delicate instruments at the command of the physicist. The experiments are further interesting for the very conclusive demonstration they afford of the causes to which the action of the instrument is due. From the first, Professor Tyndall states, he was convinced that the sounds given out by bodies upon which the intermittent beam of light impinged were due to their expansion and contraction under the influence of radiant heat, and this opinion is most fully borne out by the results obtained. The experiments, while showing the great delicacy of this beautiful instrument of Professor Bell, also incidentally show that some of the expectations with regard to it are unfounded. One of these is, that with it sounds upon the sun may be heard. The fallacy of this has been recently pointed out, and the arrangement of the apparatus adopted by Professor Tyndall clearly exhibits it. It consists in assuming that the sound given out by the absorptive body is the reproduction of a previous sound, while in reality all that is necessary is that the impinging beam be intermittent—its variations may be produced in any manner whatever.
Of the results of previous experiments confirmed by this later research, the most important are those regarding the behavior of dry air and the vapor of water toward radiant heat. By a long series of beautiful and refined experiments, Professor Tyndall had shown that the former was perfectly transparent to such heat, while water-vapor was a powerful absorbent of it. These results have been disputed by other experimenters, and it needed, to definitely settle the controversy, some more delicate method of testing these substances than that furnished by the instruments heretofore at command. This has been supplied by this latest acquisition of science, and the first use of it appears to fully sustain Professor Tyndall's position.
BOOK PHYSIOLOGY ABROAD.
We often hear subdued expressions of doubt as to the quality of the physiological teaching prevalent in girls' schools. It is intimated that the knowledge the pupils get upon this subject is generally of a very loose and vague sort, so as to be but of little practical use. It is objected to what girls learn about in their physiological studies, that it is not entitled to be called knowledge at all—that is, they do not really know what they are studying about, but only remember certain statements as well as they can, while the information they get is not of a kind fit to be used. Whatever may be the fact in regard to our own schools, it is pretty certain that the physiology taught to girls in some of the English schools is marked with all the bad qualities sometimes ascribed to our own.
The London "Globe" gives a ludicrous illustration of the results of physiological teaching in the girls' schools of the English metropolis. It seems that the National Health Society, laudably desirous of promoting the increase of practical physiological intelligence, offered prizes to be competed for by the pupils of the girls' schools under the control of the London School Board. The response, however, was not very lively. Out of two hundred and thirty-four schools only eleven sent competitors, it being presumed that in the other schools physiology is either not taught at all or so poorly taught that there was no emulation. The eleven schools which were represented in the examination, we are to suppose, were the best girls' schools under the jurisdiction of the board. Two hundred and fifteen girls attended and competed for the prizes, the examination being conducted by Mr. McWilliam, who reported the result to the London School Board.
The "Globe" says: "Many of the children appear to have been utterly unable to understand the terms of the questions. 'Mention any occupations which you consider to be injurious to health, giving reasons for your answer.' This question, Mr. McWilliam says, especially appears to have puzzled them. One girl's complete answer to this question is, 'When you have a illness it makes your health bad, as well as having a disease.' Another says, 'Occupations which are injurious to health are carbolic acid gas which is impure blood.' Another complete answer is, 'We ought to go in the country for a few weeks to take plenty of fresh air to make us healthy and strong every year.' Another complete answer is, 'Why the heart, lungs, blood, which is very dangerous.' The word 'function' was also a great puzzle. Very many answered that the skin discharges a function called perspiration. One girl says, 'The function of the heart is between the lungs.' Another says: 'What is the function of the heart? Thorax.' Another girl, in answer to the sixth question says, 'The process of digestion is: We should never eat fat, because the food does not digest.'
"Another class of errors is that of exaggerated statements, one girl answering, 'A stone-mason's work is injurious, because when he is chipping he breathes in all the little chips, and then they are taken into the lungs.' Another says, 'A bootmaker's trade is very injurious, because the bootmakers always press the boots against the thorax, and therefore it presses the thorax in and it touches the heart, and if they do not die they are cripples for life.' Several girls insist that every carpenter or mason should wear a pad over the mouth; and one girl says that, if a sawyer does not wear spectacles, he will be sure to lose his eyesight. Finally, one girl declares that 'all mechanical work is injurious to health.' Another child says that 'in impure air there is not any oxygen, it is all carbonic acid gas.' Another says that if we do not wash ourselves 'in one or two days all the perspiration will turn into sores.'
"One girl states that 'when food is swallowed it passes through the windpipe and stops at the right side, some of it goes to make blood, and what is not wanted passes into the alimentary canal.' Another girl from the same school says, 'Venous blood is of a dark black color, and when it reaches the heart it is made by the heart a bright red color.' Several girls from the same school repeat this last error. Another girl says, 'The chyle flows up the middle of the backbone and reaches the heart, where it meets the oxygen and is purified.' Another says, 'The work of the heart is to repair the different organs in about half a minute.' Another says: 'We have an upper and a lower skin; the lower skin moves at its will, and the upper skin moves when we do.'"
THE TYNDALL TRUST FUND.
It may be recollected that, at the close of his lectures in this country, 1872-'73, Professor Tyndall left all the money he had received, except what was consumed in expenses, as a trust, the income of which was to be devoted to the assistance of American students in physics desirous of completing their studies in Germany. The fund was intended, of course, for those who were without sufficient means of their own for the purpose, and was to be only available for such students as had shown an inclination for original studies, and some aptitude and capacity in pursuing them. Trustees were appointed to take charge of the fund, which was at first so small that it was thought best to let it accumulate until the income became sufficient to give a moderate support to two students. The increase of the capital has now reached a point at which the income of the trust becomes applicable for its purpose.
The original trustees appointed by Professor Tyndall were Professor Joseph Henry, of Washington; General Hector Tyndale, of Philadelphia; and E. L. Youmans, of New York. The two former are dead, and President F. A. P. Barnard, of Columbia College, New York, and Professor Joseph Lovering, of Harvard University, Cambridge, have been appointed in their places. Applications for the benefit of the trust can be made to either of the trustees.