476 



SCIENCE 



[N. S. Vol. XXIX. No. 742 



Employing a small quartz spectrograph by 

 Fuess (focus 15 cm.) 24 lines were found and 

 measured and indications of the " head " of the 

 series appeared in the plate though it was not 

 resolved into lines. 



With the large quartz spectrograph of the 

 Bureau of Standards 48 lines were resolved, 

 bringing us within 0.1 of an Angstrom unit of the 

 theoretical head of the band. The largest num- 

 ber of lines forming a Balmer series ever observed 

 in the laboratory is twelve in the case of hydrogen 

 (Cornu and Ames). Solar hydrogen (chromo- 

 sphere) shows 29 lines. The sodium series is 19 

 ahead of any Balmer series ever observed, even in 

 celestial sources. These ultra-violet lines are ac- 

 companied on each side by a channelled spectrum, 

 analogous to the channelled spectra observed in 

 the vicinity of the D lines, which form the first 

 member of the Balmer series. 



It is in the region of the channelled spectra 

 that the interesting results in the fluorescence of 

 the vapor previously described were found. An 

 attempt was accordingly made to ascertain if the 

 ultra-violet channelled spectra exhibited the same 

 phenomena. Such was found to be the case. Ex- 

 citing the vapor with the zinc spark, a strong 

 fluorescence was found to be stimulated by the 

 zinc triplet at 3344r-3302. 



Results of Some Recent Intercomparisons of Mag- 

 netic Standards hy the Carnegie Institution of 

 Washington: J. A. Fleming, Carnegie Institu- 

 tion, Washington. 



One important detail of the magnetic survey of 

 the globe undertaken by the Department of Ter- 

 restrial Magnetism of the Carnegie Institution of 

 Washington is that of the correlation of the ob- 

 servatory standards of various governments and 

 institutions. Comparisons have already been 

 made at seventeen observatories in various parts 

 of the world; the results of the four most recent 

 intercomparisons were discussed in detail in the 

 paper and may be summarized thus: The fol- 

 lowing corrections should be applied to the pro- 

 visional standards of the Department of Terres- 

 trial Magnetism of the Carnegie Institution. 

 The probable errors of mean differences are given 

 with them. For Kew Observatory; declination 

 + 0'.G±0'.15, horizontal intensity — O.OOOlff 

 ± .00005ff, inclination — 2'.6±0'.1. For Hel- 

 wan; dec. + 0'.5 ± O'.l, hor. intens. -f 0.0004H 

 ±.00004ff, inclin. + O'.l ± O'.l. For Tiflis; dec. 

 + 0'.7, hor. inten. + .OOOGff ± O.OOOOGff, inclin. 

 — I'.T ± O'.l. For Christchurch; dec. + 1'.5 



± 0.04, hor. inten. + O.OOOGff ± .OOOOGff, inclin. 

 — 1'.2 ± 0.3. 



The values are to be applied algebraically, east 

 declinations, north inclinations and horizontal in- 

 tensities being considered positive, and west decli- 

 nations and south inclinations, negative. The 

 preliminary " International Magnetic Standard " 

 for horizontal intensity is confirmed in view of 

 the accordance of the correction at Kew with the 

 indications of Watson's determinations of the 

 earth's field in international imits. 



A Critical Review of the Prohlem of Pressure in 

 the Kinetic Theory of Qases: LuiQl D'AuKLi, 

 Philadelphia, Pa. 



This paper seeks to show that the recognized 

 method of solution of this problem is erroneous 

 and the gaseous pressure per unit area is equal 

 to the energy of agitation of the gas per unit 

 volume. It will be printed in Popular Astronomy. 



The Dynamophone: J. Bubkett Webb, Stevens 



Institute of Technology. 



Some years ago the problem arose of measur- 

 ing the power which a turbine transmitted 

 through its shaft to the propeller. The ordinary 

 " indicator " being useless, a method depending 

 on the torsion of the shaft was invented. As it 

 was the intention to protect it by patent, it could 

 not be published sooner, but it has leaked out 

 somewhat and more or less incorrect references 

 to it have appeared in (Jerman papers. 



The first idea was to measure the torque optic- 

 ally, but a better method was adopted. The 

 apparatus necessitates no mechanical contact with 

 the shaft and the speed can also be observed 

 without the usual speed counter. The degree of 

 accuracy is very high, there being no difficulty in 

 making single observations within one per cent, 

 of error. 



The apparatus consists of two toothed iron 

 rings which are fixed permanently to the flanges 

 of the shaft at as great a distance apart as pos- 

 sible. Opposite these rings on a frame fast to the 

 floor are mounted telephone magnets adjustable 

 radially and concentrically as to the shaft axis. 

 Each ring and magnet (or pair of magnets) con- 

 stitutes an alternating dj-namo whose current in- 

 tensity can be regulated by the radial adjustment 

 of its magnet and whose phase can be varied by 

 the concentric movement, and these two dynamos 

 are connected in series so that when the shaft is 

 not twisted their phases are opposite and neutral- 

 ize each other in a receiver inserted in the cir- 

 cuit. When, however, the shaft twists the phases 

 become different and a clear tone is perceived. 



