20
NOTE ON THE KATA-THERMOMETER.
1:y LEONARD HILL.
[Xatianal Institute for Medical Eesorsrrh, h d o n , Feh. 1, 1922.1
In an tirticlt! ublished in the MONTHLY WEATHRP.
men t tind Health, the katu-thermometer wais de- scribed tind forniulae for it given connecting tempw .I t urv
and wind. These forniulae were worked out in :I simrll
wind t.unne1 12 inches in diameter, a.s, during t,lw MW.
it was not ossible to use the large wind tunnels in thth
airplane work there. Since the axmustice t.hesc. tunnels. from 3 to 7 feet in dia.nieter, have been av;i.ilnble for us t o
redetermine very exactly the i kata formula for higher velocities. For low velocities we ha.ve used t,lie whirling arm method, rotating the kata on the airin, whicdi IS
moved through the air at known velocitv, nnd 11iikking H
suitable deduction for the  swirl effect. The dry kata has proved most useful tis i ~n tine- mometer for determining the very low velocities of air movement which esist in rooms and workshops, nnd .for
REVIEW,^ in wliic P 1 1 dealt with  Atniospherjc En\-iron-.
National P P iysical Laboratory, owing to the pressure of
this purpose the formula
H = (0.20+0.40,/~)e
should be used, where  H = cooling power katai v=velocity in met,e,rs per second! .5 C. minus the temperature of the air. For velocities above 1 meter per second, to be used is
H = (0.13 + 0.47-,/GM
of the dry and 0 =:3fi0
the forniulu
Using this formula, very good agreement has been obtained between measurementns of wind macle 0 ) by the  kata, (2) by stanyard cup anemometers. The formulae and data me published in full in t.lie
PTOC. Roy. soc. R, 1982.
A CORRECTIVE NOTE ON RAIN-GAGES.
I%y S. I?. BEBGUSSOX, Meteoro1-t.
[Weather Bureau, &shlngton, D. C.! Feb: !2S, lg2L.1 ,
The EDITOR has receiqed &he-followin lettef -from Dr. Charles Chree. Assistan t,.Director of t-he 5 ri tish Meteoro- logical Office :
.. . . . .- .... - .. . _.
840: 887-690.1O20.
receipt of Dr. Chrees letter, a brief examination of older libmt~re was undertaken and. II Treading of Symons
 History of the Rain-Gage (Quunterly Journal, Royal Xdkorotoqical Society, lSSl), reveded n brief reference to a gage of this piittern su geste4 by Leupold (1726),
were overlooked by the writer w%en reading this raper
ninny years ago. Also, Prof. Talmm kindly supp led R
i i ctitalog issued by Hicks of Londod in lS87, illust,rating
i1.11 instrument similar in principle, pcitented and xtian- uf:ictured by him. Consequently, . the stat.enient, t,liat t.he principle of this instrument, is niw is incorrect.
tn suggesting t.his form of gnge the writer hiid in mind chiefly an instrument for use a t isaln ted s t.a tions where precipita.tion is excessively large &nd recording gages c:in not be used. As Dr. Chree st,ates, t,his inst,rument
is not suitable for a region of light. brecipitation, and for
general use it is far less convenient nnd acriirri.te t.hrin n
good recording gage.
and another by Stutter (.no d Rte aiven) ; these. references
THE AURORA OF MAY 14 TO 15, 1921.
By 1T. 11. (LAYTON, (hief of the Eorecpt Division of the t\rgent,ine Weather Service.
The following, reports of the brilliant aurora of May 14
to 15, 1931, which ac.com mied two immense spots near the center of the sun amflit up both hemis heres of the mrth, have come into the Argentine Meteoro P ogical Office. Owing to the fact that few re orb of aurora come from the Southern Hemisphere, I tfink these will be of inter- est to your readers. From Chmberland Ba , south Georgia, to the director
June 3, 1921:
DEAR SIR: !!apt. P. 86rlle. of the Ranhefjord Whaling (70.. inform 1
me that on the night of $ray 14 to 15 he saw the entire sky toward the southeast lit up aa i f by an immense fire. According to the account of Capt. 86rlle and other whalers there was a magnificent displav of light which increased and decreased from tinie to tinie. They thought it arose from a wlcanic emption in one of the islands of the Sandwich group (1st. .5SG S., long. ?5@ W.). (!apt. SGrlle was there in the pear 191 1 during the volcanic erulition
of that epoch and escaped from the tire almost by Y miracle. etc.
of tlie Oficina Meteoro Q ogica Argentina, G. 0. Wiggin,
Respectfiilly . THORLEIP HOXXARK.
SantsCruz, iirgentinu to the Director of the Oficina Meteorologica, Geo. 0. diggin, September 9, 1921 :
DEAE SIR: AE requested. I am sending you the following description of the aiiroisL of May 14,1921. A t 11:15 p. m. (23:15h3 a luminosity was
noted in the sly toward the south and south-southwest. 80 that a layer of cirrus and cirro-atatus could he clearly diatinguiahed. The appearance of thesky slowly rhanged as the luminosity increased and took on a tint at first slightly rosv. increasing in intensity until the color was almost. crimson. The fir& pulsations were visible at 11:40
1. ni. i 3 4 0 h 1, being st. first of slight intensity and appearing in the
forin of short Iuminous rsys in continual movement. a~ well in a hbri- xontal as in a vertical direction. Little by little the pulsations of the rays became stronger and more frequent, and they showed different forms. at times in visible niove- m a t . then disapj~earing and afterwards retlirning suddenly with new force. Very frequently there were ala0 r a y as i f a searchlight had been turned toward the zenith. The q)ect,acle lasted until 130 a: m. of the 15th. gradually decreaaing in intensity and frequency. and finally there only remained the last- mentioned rays. which were directed toward t.he zenith. There are some pemm who sa?; that tlie rays were wen iintil 4 to 5
a. in. of t,he 15th. I~~spertfiilly,
I[. \\ANI:C).