tjrases. Boyle's Law. Rayleigh (Philosophical 

 .transactions, April 12) used for experiments on 

 this law two gages, which, as determined by test- 

 ing them in parallel, indicated pressures in the 

 ratio of 1 : 0.99862. A volume of gas was taken 

 with the pressure indicated by one of these gages, 

 and it was then compressed till the pressure was 

 that of the two in series, its new volume being 

 noted. It was thus found that, to an accuracy 

 of ydW) a * r > hydrogen, oxygen, and argon obey 

 Boyle s law at the pressures and temperatures 

 (10-15 C.) of the experiments, while nitrous oxid 

 deviates from it in having greater compressibility. 



Vortex Rings. A. Indra (Vienna Academy of 

 Sciences, April, 1901) describes experiments with 

 the well-known smoke ring, the box used having 

 transparent sides. When a direct ring issues 

 from the aperture, a conjugate ring enters the 

 box, its rotation being in the opposite direction. 

 Experiments with direct rings show phenomena 

 analogous to reflection, refraction, and absorp- 

 tion. The author believes that vortex rings play 

 no part in the dispersion of storm-clouds by can- 

 non firing, since experiments shows that they can 

 not reach a sufficient altitude. He attributes the 

 effect to sound-waves. 



Sound. Stability of Vibration. C. Barus 

 (Science, Sept. 13, 1901) finds that when a resona- 

 tor is gradually moved toward an organ pipe, 

 under certain conditions the following phenomena 

 are observed : With the aperture of the resonator 

 toward the pipe, the note rises from c" to d" at 

 a distance of 1.1 centimeter. For smaller dis- 

 tances the note returns to the original c". For 

 larger distances destructive interference occurs. 

 If the closed end of the resonator be toward the 

 pipe, a flattening of the note occurs. Like effects 

 are produced if the resonator be appi'oached to 

 the top of the pipe instead of to the slit. The ex- 

 planation is that in the vibration of a system un- 

 der friction having one degree of freedom a cer- 

 tain amount of damping occurs. The open end 

 of the resonator diminishes the damping to such 

 an extent that the pitch is raised. The closed end 

 increases the damping with contrary effect. 



Air-Pressures in Brass Instruments. E. H. 

 Barton and S. C. Laws ([London] Physical So- 

 ciety, Dec. 13, 1901) have examined the relation- 

 ship of the pressure of blowing to pitch, intensity, 

 and method of fingering in several musical in- 

 struments. The following results are arrived at: 

 " (1) The louder the note the greater the pres- 

 sure ^ (2) the higher the pitch the greater the 

 pressure; (3) for a given intensity, the pressure 

 is approximately proportional to the logarithm of 

 the frequency; (4) alternative methods of finger- 

 ing have practically no effect on the pressure re- 

 quired, pitch and intensity being kept constant; 

 (5) the pressures for cornet and trumpet are al- 

 most the same, the same note being produced at 

 the same intensity ; the pressure for the trombone 

 is very much greater." 



Decimal Musical Scale. A. Guillemin (Comptes 

 Rendus, April 28) proposes to replace the oc- 

 tave and the comma, (the usual large and small 

 units of interval) by the savart and the millisa- 

 vart, defined as follow: The savart to be the 

 interval 10:1 (3 octaves and a major third) and 

 the millisavart the thousandth part of this (ap- 

 proximately 435 to 434). With these units all 

 calculations will be much simplified. The tem- 

 pered semitone is very nearly 25 millisavarts, and 

 the millisavart, although not appreciable directly 

 by the ear, may be easily apprehended by the 

 beating, at the rate of one per second, of the notes 

 435 and 434. It is proposed that the standard 

 international fork should be taken as 434.3. 



PHYSICS, PROGRESS OF, IN 1902. 



547 



Heat. Thermomctry. L. Holborn (Annalen 

 der Physik, October, 1901) has examined. various 

 substances to find one suitable for liquid expan- 

 sion thermometers for temperatures as low as the 

 boiling-point of liquid air. Petroleum ether was 

 finally adopted, but as it is scarcely a definite 

 substance, it is not altogether satisfactory. The 

 ether used was distilled from a commercial sam- 

 ple boiling at 33 C. The authors compare pe- 

 troleum thermometers with platinum thermome- 

 ters, and tabulate the deviations at different 

 temperatures on different days. O. Lummer and 

 E. Pringsheim (Physikalische Zeitschrift, Dec. 1, 

 1901) find that the radiation laws can be made 

 serviceable for temperature determinations, fur- 

 nishing a new temperature scale, which is identical 

 at low temperatures with the usual gas thermome- 

 ter scale, but can be utilized at much higher tem- 

 peratures than the method of the gas thermome- 

 ter permits of. F. Kurlbaum (Physikalische Zeit- 

 schrift, Feb. 1) employs an optical pyrometer de- 

 vised by Holborn and himself to measure the tem- 

 perature of flames. An image of the flame is 

 formed on the filament of a glow-lamp, and the 

 latter is heated by a current until it ceases to be 

 visible through red glass. This method gives 

 lower estimates of temperatures than Lummer 

 and Pringsheim's (for example, 1,431 C. for a 

 candle instead of 1,582). It can only be employed 

 when the luminous carbon particles in the flame 

 are not surrounded by absorbent gases. A. Job 

 (Comptes Rendus, Jan. 6) describes a method of 

 utilizing the viscosity of a gas in thermometry 

 a suggestion due to Barus and Callender. A 15- 

 per-cent. solution of soda is placed in a bottle in 

 whose stopper are three holes two for electrodes, 

 and one to allow electrolytic gas to escape. This 

 gas passes through a fine porcelain tube, in which 

 lies a platinum wire. If the tube is placed in a 

 furnace, the viscosity of the gas decreases and 

 the volume escaping increases. The relation be- 

 tween the temperature and the pressure of the 

 gas on entering the porcelain tube is a linear one, 

 and the former can therefore be ascertained by 

 reading the latter by a sensitive manometer, cali- 

 brated by comparison with a known thermome- 

 ter. 



Radiation. Compan (Comptes Rendus, Nov. 18, 

 1901), in order to investigate the laws of radiation 

 at low temperatures, experimented on the cooling 

 of a ball of copper 2 centimeters in diameter, 

 blackened and of maximum emissive power, 

 suspended in a glass globe, the pressure in 

 which could be increased or diminished at pleas- 

 ure. The vacuum in the globe being first of all 

 pushed to its extreme limit, the ball was heated 

 without removing it by projecting on it, by means 

 of a lens, the positive crater of an electric arc. 

 In this way its temperature could be raised above 

 320. The globe was plunged in a freezing mix- 

 ture, and the rate of cooling was measured thermo- 

 electrically with different ranges of temperature 

 between 302 and 182.5, the values obtained 

 being compared with the formulae that express the 

 laws of Dulong and Petit, of Stefan, and of Weber. 

 The first of these laws was found to apply only 

 from to 200. That of Stefan agrees fairly well 

 from the temperature of liquid air up to 302, 

 yet it is somewhat too high above 150. Weber's 

 law applies well only from 100 to 302. 



Mechanical Equivalent. H. T. Barnes (Elec- 

 trician, 45, p. 969, 1900) has redetermined the me- 

 chanical equivalent of heat by imparting electrical 

 energy to a constant stream of water, so as to give 

 a steady difference of temperature at its ends. He 

 finds the equivalent to be 4.18876 joules a result 

 about 0.132 per cent, higher than those that Rey- 



