is long retained whether the current is thereafter broken or not. It is gradually dissipated, however, as the joint at the telephone plate is rarely quite tight; and when the teleg' to b' C"

5

phone sounds, pressure increments may even become negative, as above. If most of the water is removed by bibulous paper a moderate fairly constant pressure is usually observed for some time, until (doubtless with the breaking of the film across the hole) the maximum is suddenly again attained.

7. Inside and Outside Stimulation.-When the tube c' is inserted within the rubber connectors t, t' in the absence of vents, there is much undesirable pressure disturbance at the outset, which is but very slowly dissipated. Moreover the closed space can not be opened again at pleasure without similar commotion. I, therefore, used the apparatus, Fig. 6, in preference, in which the pinhole tube c' is provided with a branch tube t" and cock C. The rubber tube t leads to the telephone (beyond T) and the tube t' to the mercury U-tube (beyond U). If C is open, c' may be inserted or withdrawn with facility. If C is closed the resonator R is closed, as in the above case. Using the mercury interruptor (frequency c) with 2,000 ohms in circuit the deflection of the closed region was invariably negative. The deflection is peculiar, moreover, inasmuch as it is a slow growth within a minute or more, to a maximum. On breaking the current the deflection dies off in the same slow fluctuating way. If the cock C is opened, the zero is instantaneously recovered. In other words the dilation is due to a loss of gas within the closed region, which loss is but slowly restored after the telephone ceases to vibrate.

If the cock C, Fig. 2, is opened at the critical point, or if it is replaced by the tube c, the deflection is again positive. The action of c thus exceeds that of c', probably because the pinhole in c happens to be nearer the critical size than in c'.

The question next at issue is the influence

There is thus an enormous maximum dilatation somewhere in the range of frequency d", e", which from the hovering character of the deflection is not further determinable. This amounts to a pressure decrement of Ap-6X 10-3 cm. of mercury with 2,000 ohms in the telephone circuit. At 100 ohms it would have been about a millimeter of mercury.

The slow growth of relatively enormous pressure decrements here recorded is so surprising that further experiments are needed. To begin with one may ask whether the telephone plate, held as usual by strong screw pressure between annular plates of hard rubber, is adequately airtight. I therefore removed the telephone and sealed all these parts with cement, thoroughly.

On replacing the telephone with the adjustment as in Fig. 6, the behavior had in fact changed, the negative pressure being of the small value indicated in §2, without growth in the lapse of time. In other words the presence of the pinhole c' within the closed region was now ineffective.

We may summarize these early results for the particular frequencies used, as in Figs. 9 and 10. In an air region R, closed on one side by a vibrating telephone plate T and on the other by a quiet plate U, the pressures are distributed as if there is a maximum at T and a minimum at U. If the region R, Fig. 9, communicates with the atmosphere by a pinhole O of the critical diameter, the pressure within R is raised as a whole by the amount which the pinhole air valve will withstand. Again if the closed region T U, Fig. 10, contains a pinhole valve O within only, it does not differ essentially from the corresponding case in Fig. 9; but if an additional very fine leak O' is supplied on the T side, Fig. 10, the U side gradually develops a large pressure decre

ment; whereas if the pinhole is supplied on the U side, this develops the usual pressure increment. In the former case air leaks out of O' diffusively; in the latter it leaks into O".

After many trials, however, only in one case did I succeed in obtaining pressure decrements with pinholes, screw cocks, etc.; this when lost could not be recaptured; but all the present and following results in acoustic dilatation were strikingly reproduced by put ting a new telephone with unsealed plate in circuit.

With the apparatus, Fig. 1, and the cock C opened at the critical point, a diapason c" blown in the vicinity of the cock was easily identified and the octave c"" even three times as active (15 fringes). In another adjustment, the shrill overtone gave nearly 100 fringes. There is some misgiving in interpreting these data, as the open mouth of the pipe must usually be closed to the mouth of the cock; but as the overtone was still appreciably effective six inches to a foot away, the results are probably trustworthy.

8. Effect of Resonance.-While a parallel relation of the maximum pressure to the frequency of the telephone note has been shown to exist, it is obvious that the best conditions for high maxima will occur under conditions of resonance between the natural R and the T vibrations (Fig. 1) or their harmonics. I, therefore, used the same small induction coil with two storage cells, but with a commutator-like current-breaker, controlled by a small electric motor with a variable resistance in circuit (electric siren). By gradually decreasing this resistance all chromatic intervals between about f' and a" were obtainable. The speed of the motor, however, fluctuated slightly, while intervals within a semitone often produced large pressure differences. Thus the determinations of the intervals of a somewhat flickering pitch in all chromatics is quite difficult, even for a musical ear. A series of organ pipes within the given range seemed to offer the best standards of comparison, as it was necessary to turn rapidly from one series of observations to another.

In this way the graphs given in Figs. 7, 8, were worked out, the curves showing the fringe displacement s the logarithmic frequency n of the telephone. In Fig. 7, to limit the deflections within the range of the ocular, about 2,000 ohms were put in circuit. Three maxima and three minima (one positive and two negative) are indicated. The maximum below f' could not be reached. The strong one at c" was well marked and approachable from both sides. The small one near g", though easily observed by continuously changing the pitch, was difficult to record.

The latter, however, is particularly interesting as it introduces the strong pressure decrements at a". I, therefore, reexamined it in Fig. 8 with less resistance (1,000 ohms) in circuit and the results came out more clearly. The deep minimum at a" deserves further investigation, as it precedes a probably very high maximum at the near c"". At least this may be inferred from the stimulation produced by an organ pipe used on the outside of the apparatus, §7. Something better than the electrical siren used will have to be devised; but apart from this the results are very definite.

Adjusting the siren for the maximum c", the sensitiveness with different resistances in circuit (2,000-9,000 ohms) was determined. The curve is shown in series 9, Fig. 3, and is the highest thus far obtained. The equation, rs constant, does not fit so well here, a result inseparable from the slightly fluctuating note; for this makes a big difference in the maximum. The mean value is about Ts= = 80 X 103. Referred to a circuit resistance of 100 ohms this is equivalent to a deflection of 800 fringes and a pressure of Ap=.024 cm. of mercury.

An auxiliary telephone placed in circuit with that of T, Fig. 1, affords no suggestion of these occurrences. Its notes rather increase in strength regularly with the pitch. Yet if the note should happen to be near e", the other telephone would show no deflection.

Finally the use of the pin hole vent as a probe to detect the distribution of compression

in organ pipes has been very fruitful; but these results will have to be omitted here.

9. Reversal of Poles of Telephone Changes Sign of Fringe Deflection.-An earlier detection of this result would have saved me much mystification. Not expecting it, I did not look for it; but it seems that a reversal of the telephone current (so to speak) reverses the fringe deflection, symmetrically. It is merely necessary to add a switch to the telephone circuit to prove this. Moreover for a given position of the switch and in the proper order of frequency, pressure increments pass continuously into pressure decrements (Fig. 7).

curve

To test the case further, I used the motor interruptor, making a survey for frequencies between g' and a" with the switch reversed and the sealed telephone. The new corresponded very fully to the curve, Fig. 7, except that maxima and minima had been exchanged. Thus the apparatus regarded as a dynamometer would, with a proper selection of frequency, give both quantity and sign of the impulsive currents in the telephone.

Since the resonating region R is vented by the pinhole, the positions of equilibrium of the quiet and of the vibrating plate are ineffective. Hence it is necessary to assume that the vibrations of the plate are here not symmetrical; or that, for instance, the impulse corresponding to the break of current at the interruptor is of excessive importance.

A closed region may be filled with an excess of compressed wavefront successions, provided means are at hand for the supply of the extra air needed and the energy dissipated; conversely, the closed region may be filled with an excess of rarified wavefront successions if the outflow of superfluous air is possible. In both cases the vent must be so small as to leave the region virtually closed. A ray of light imprisoned in a chamber closed with perfect mirrors might be considered as analogously circumstanced.

10. Removal of Pressure Decrements Associated with Pressure Increments.-Marked pressure decrements occur near the minima at c" and a" in case of the prolonged tests

in §8. One may, therefore, suspect that (as in §7), the decrements result from an insufficiently tight joint at the telephone plate. The telephone with sealed plate was, therefore, carried through the chromatic series of notes from f' to a". It is needless to give the data here, because they resembled Figs. 7 and 8 in character, except (as was anticipated) that there were no pressure decrements at the minima. In fact the maxima (below f' at c", g" and above a") came out more sharply than in Figs. 7, 8 and the now positive minima (near g', d", a") equally so. It seems as if the ordinary overtones in the key of C were in question.

Replacing the sealed telephone by the usual apparatus with clamped plate, the results of Figs. 7, 8 with marked dilatations at the minima were reproduced at once, except that the maxima (a', c", a") were in the key of A, in accordance with the increased volume.

Finally I tested the above telephone with sealed plate again and found that pressure decrements at the minima associated with pressure increments at the maxima (as in Figs. 7, 8) had reappeared. These relations were exchanged on reversing the current. I suspect, therefore, that the potent influence is the mode of vibration (modified by sealing) of the telephone plate itself. About this I shall have something to say in the near future, showing that each inductive impulse is followed by shock waves in the plate, of relatively very high frequency compared with the frequency of induction, just as an anvil rings after each blow of the hammer.

BROWN UNIVERSITY, PROVIDENCE, R. I.

CARL BARUS

THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE DUTY ON SCIENTIFIC APPARATUS FOR EDUCATIONAL INSTITUTIONS

THE following resolution regarding dutyfree importation of scientific materials and scientific books in the English language into the United States by educational institutions have been passed by the American Association for the Advancement of Science:

WHEREAS, the scientific education of the youth of the United States is among the most fundamental and important functions of the Republic, education being the only means by which the advantages of present civilization may be surely transmitted to coming generations of citizens and by which the future progress of the Republic may be assured; and

WHEREAS, the prosecution of the said scientific education of the youth requires unrestricted employment of the apparatus and materials of science in educational institutions, this being increasingly true for more advanced education; and

WHEREAS, the scientific materials and apparatus to be used in educational institutions ought to be selected, as far as possible, without consideration of their place of origin, since science is worldwide in its scope; and

WHEREAS, any increase in the cost of scientific equipment for education is to be greatly deplored, since the funds available for its purchase by edu cational institutions are invariably inadequate in comparison with the great needs and possibilities of education; and

WHEREAS, institutions for higher education must still be relied on for the most fundamental and farreaching steps in the advancement of knowledge, through the scientific researches of their faculties and students; and

WHEREAS, both financial and patriotic considerations clearly require that the Republic should aid fundamental scientific research in every possible way, especially avoiding the erection of artificial barriers across the path of the advance of true knowledge; and, finally,

WHEREAS, in consideration of the foregoing clauses, The American Association for the Advancement of Science, with its 12,000 members, almost all of whom are citizens of the United States-representing the fundamental scientific interests of the country from the standpoint of scientific research as well as from that of instruction, and representing especially the institutions for higher education and their staffs-views with very serious concern the proposal to repeal section 573 of the tariff act of October 3, 1913, which allows the duty-free importation of scientific materials by educational institutions; therefore, be it

Resolved, that The American Association for the Advancement of Science respectfully calls the attention of the Congress of the United States to the very great hindrance and burden that would be imposed upon the scientific education and research in

the Republic if its educational institutions were to be deprived of the privilege of duty-free importation of scientific apparatus and materials, which they have enjoyed for many years; and be it further

Resolved, that the American Association also respectfully urges the restoration of the corresponding privilege of duty-free importation of single copies of scientific books in the English language by recognized educational institutions and the faculties, such books constituting an important item of both institutional and personal equipment for advanced instruction and research, especially since it is undesirable that scientific publications in languages other than English should be artificially favored in the United States; and be it finally

Resolved, that these resolutions be forwarded to the proper committees of the Congress of the United States, to the National Academy of Sciences, to the National Research Council, and to the secretaries of the scientific societies affiliated with the American Association, that they be published in SCIENCE, official organ of the association, and also that they be sent to each member of the association.

SCIENTIFIC EVENTS

'SCIENCE' AND THE PRINTERS' STRIKE

THE printers of SCIENCE are making special efforts to bring out the journal in spite of the general strike of compositors affecting the offices in which most of our scientific journals are printed. In order to assist them, the present number is reduced somewhat in size and is using mainly matter in type prior to the strike. The present issue gives first place to an important article which under ordinary circumstances would be printed in the department devoted to special research. It may again be noted that the advertisers have been requested to use copy already in type.

The Council of the American Chemical Society voted at their recent Rochester meeting:

That this council expresses to the directors of the society the hope that the Eschenbach Printing Company will be released from any forfeits that may arise under the terms of its contract in connection with the impending strike, due to the insistence upon the 44-hour week, and

That the members of this council also express their willingness, in the event such a strike is not amicably settled, to wait indefinitely for the publication of the journals of the society.

THE BRITISH INSTITUTE OF PHYSICS 1

THE Institute of Physics was inaugurated at a largely attended meeting in the hall of the Institution of Civil Engineers on April 27. The need has long been felt for a corporate body, analogous to the Institute of Chemistry, which should strengthen the position of workers engaged in physics, and form a bond between the various societies interested in the subject. The institute has now been founded by the cooperation, in the first instance, of the Faraday Society, the Optical Society and the Physical Society of London, while the Royal Microscopical Society and the Roentgen Society have since decided to participate. In opening the proceedings, the first president, Sir Richard Glazebrook, said that the work of the physicist would become more and more important in the future, both in pure and applied science, and one of the aims of the institute was to accelerate a recognition of the

physicist's position and value. Many developments in physics had been of vital importance during the war, but men who had done important work as physicists could only be given an official status in some cases by being termed research chemists. He added that the membership of the institute was already about 300, and comprised most of the leaders in physical science. Sir J. J. Thomson, who, it was stated, was willing to be nominated as president for the next year, gave a brief address. He said that to one who regarded chemistry as a branch of physics it was rather anomalous that hitherto there should have been an Institute of Chemistry and not an Institute of Physics. He had been a student of physics for fifty years. At the beginning of that period physics was like an army with great generals but few troops. There were at that time perhaps a dozen laboratories in the country. Opportunities multiplied rapidly, however, and students with them, and salaries also increased so that

1 From the British Medical Journal.

physics now offered to every competent man a livelihood though but small hope of a fortune. To-day the demand for competent physicists exceeded the supply. Research was expensive for the student and for the university, and perhaps this fact was not sufficiently recognized, although more money was available for research now than ever before. He saw no disposition to neglect or undervalue pure research, undertaken without any thought of an industrial application, and he congratulated the institute on representing a profession which not only contributed so largely in various ways to human comfort, but aided the intellectual development of mankind. The Right Hon. A. J. Balfour extended a cordial welcome to the Institute. He had been greatly surprised to learn that there was not already in existence an institute of physics. After all, physics was the most fundamental of all the sciences. Whatever a man's line of research might be, if he could find a physical explanation for the phenomena he was examining, then, and then

only, could he hope for something like finality in his investigation. It was certainly surprising that in this country, which had not

lagged behind any country in the world in the great advances it had made in regard to the

physical knowledge of the universe, they had not had an institute of physics before now.

THE BOSTON MEETING OF THE AMERICAN MEDICAL ASSOCIATION

THE seventy-second annual session of the American Medical Association will be held in Boston, Mass., June 6-10, 1921, under the presidency of Dr. William C. Braisted. The scientific assembly of the association will open with the general meeting to be held at 8:30 P.M., Tuesday, June 7. Sections will meet Wednesday, Thursday, and Friday, June 8, 9 and 10 as follows:

The

Convening at 9 a.m., the Sections on Practise of Medicine; Obstetrics, Gynecology and Abdominal Surgery; Laryngology, Otology and Rhinology; Pathology and Physiology; Stomatology; Nervous and Mental Diseases; Urology; Preventive Medicine and Public Health.