J 54 



NATURE 



[June 17, 1897 



Immunity from Mosquito Bites. 



The note of your correspondent (Nature, No. 1438), relative 

 to the above subject, leads me to point out that my own ex- 

 perience is the counterpart of that there presented. More 

 than twenty years ago, as a young man, I camped during the 

 months of May and June in the forest which bordered the 

 south shore of Lake Superior, a region teeming with varied 

 forms of insect-life, among which the mosquito held a con- 

 spicuous although not the most obnoxious place. I had pre- 

 viously been very sensitive to mosquito stings, and sufifered 

 acutely from them during the entire period spent in camp, 

 my hands and face being so closely covered with the peculiar 

 ihard lumps resulting from the sting, that they presented in 

 place of soft flesh only a series of contiguous swellings. 



The temporary discomfort thus occasioned has since been 

 abundantly recompensed. For many years afterwards mos- 

 ■quitos displayed a marked antipathy towards my blood, rarely 

 stinging me if any other person were available as a subject 

 for their attacks. This kind of immunity I have now par- 

 tially lost, but even to the present time a mosquito sting 

 occasions me very little annoyance. It is followed by no swell- 

 ing, and the pain ceases within a few moments after the 

 proboscis is withdrawn. Geo. C. Comstock. 



Washburn Observatory, Madison, Wis., U.S.A. 



Sound Signals in Fog. 



Referring to one of your Notes on page 130, I will take 

 •the opportunity of repeating a suggestion which I have several 

 times made privately, vir. to have on board ship not a double 

 emitter but a double receiver of sound : — a pair of trumpet- 

 mouths or collectors or ears, one at each side of the ship, with 

 the bulk of the ship as a shadow-throwing object between 

 (like the head), and with tubes leading from them into the 

 the captain's or other quiet cabin. The listen-out-man, having 

 these tubes in his ears, would be able to hear distant sounds 

 and estimate their direction with greater precision than if he 

 trusted to his own small collecting organs, but I apprehend in 

 just the same sort of way, and almost without training. 



June 12. Oliver J. Lodge. 



Fire-fly Light. 



In answer to Prof. Silvanus Thompson's inquiry in Nature 

 of June 10, it may be stated that the " Johanniskafer," or 

 " JohanniswUrmchen," is the common glow-worm, Lainpyris 

 noctiltica, L., or Lampyris splendidida, L. E. Overton. 



Zurich, June 12. 



THE APPROACHING TOTAL ECLIPSE OF 

 THE SUN. 



npHE failure of so many of the eclipse parties last 

 ■*■ year to secure observations, makes it a matter of 

 •congratulation that the weather prospects of the eclipse 

 to be observed in India on January 22 next year seem to 

 be as favourable as they possibly can be. I propose in 

 the present article to refer generally to the objects to be 

 attained, and to give an account of the proposed arrange- 

 ments so far as I know them ; and to show how fair the 

 prospect of success this time is, I will begin by referring 

 to a note drawn up by Mr. Eliot, F.R.S. Meteorological 

 Reporter to the Government of India, in order to give 

 the chief meteorological features of the tract of country 

 in India through which the line of totality will pass. 



The note begins by giving a general idea of the Indian 

 climate. 



"It may be premised that the year in India may be divided 

 into two seasons or periods— the north-east or dry monsoon (or 

 season), and the south-west or wet monsoon. During the 

 south-west monsoon winds of oceanic origin prevail, and the 

 whole of the period is one of frequent rain over the greater part 

 of India. The chief features of this period, lasting from June to 

 December, are moderately high temperature, moderate diurnal 

 4-ange of temperature, high humidity, much cloud, and more or 



NO. 1442, VOL. 56] 



less frequent rain. The amount of cloud and rain differ very 

 considerably in different parts of the country, depending upon 

 their position with respect to the neighbouring seas and the 

 mountain ranges in India, and other conditions. The south- 

 west monsoon winds usually withdraw from Northern India in 

 September or October, and from the Bay of Bengal and 

 Southern India in December. Hence the months cf November 

 and December form a transition period from the conditions of 

 the wet to the dry monsoon, the change commencing in Upper 

 India, and extending slowly eastwards and southwards. 



"During the dry or north-east monsoon (extending from 

 January to May), winds of land origin prevail in the interior of 

 India. In Northern India these land winds blow down the 

 larger river valleys, and are hence westerly over the Gangetic 

 plain, the largest river plain in India. 



" The first two months, January and February, form the cool 

 weather of Northern and Central India and the Deccan. The 

 mean temperature of the day ranges between an average of 71° 

 in the Deccan (Berar, the Central Provinces, and Hyderabad), 

 and 54° in the Punjab. The diurnal range of temperature is 

 large in amount, varying between 25° to 35° or 40° in the 

 interior. The air is usually very dry, skies free from cloud, and 

 winds light, more especially in the Punjab and more remote 

 districts of the interior. The disturbances of this period are 

 feeble cyclonic storms of large extent, which cross Northern 

 India from west to east, and give much cloud and light, to 

 moderate rain in the plains and hills of Northern India. Tem- 

 perature increases rapidly in March, and that month and the 

 two following months of April and May form the hot weather 

 season. The intensity of the hot weather conditions increases 

 from March to May. The chief features of the weather of this 

 period in the interior of India are high day temperature, large 

 diurnal range of temperature, great dryness of the air, and 

 strong day winds which raise clouds of dust, and more or less 

 obscure the sky and sun. Cyclonic storms of large extent are 

 of comparatively rare occurrence in this period. On the other 

 hand, small local hot weather storms — including hailstorms, 

 thunderstorms, and duststorms — are of frequent occurrence, and 

 tornadoes are of occasional occurrence, in Bengal chiefly." 



It follows from this sketch that the eclipse will occur 

 in the middle of the cold weather and at the most favour- 

 able time of the year for travelling in India. Light 

 north-east winds, fine weather, and smooth sea are to 

 be expected. Cyclonic storms are of exceedingly rare 

 occurrence in either sea during the month, and the chance 

 of a gale or of stormy weather in the month off the 

 coast of the Konkan (from Bombay to Karwar) is, accord- 

 ing to Mr. Eliot, less than 1/50. He states : — 



" The weather is throughout the month of January almost 

 uniformly fine, with clear or lightly-clouded skies over the whole 

 of the Peninsula. Light north-easterly to easterly winds obtain 

 in the Deccan, or interior of the Peninsula. The west coast 

 districts are protected by the West Ghats from these winds, and 

 light land and sea breezes prevail. The most remarkable feature 

 of the meteorology of the coast area from Bombay south to Kar- 

 war in January is the freedom of the skies from cloud. Dis- 

 turbances are of very rare occcurence, and fine weather is hence 

 almost a certainty during the whole of the m^nth. There is, 

 however, usually much dust in the air, raised by the dry winds 

 in the Deccan." 



Among other most important matter in Mr. Eliot's note 

 is a table showing average temperature, humidity, cloiid 

 and rainfall data in January at certain stations in India 

 near the line of totality. We gather that the mean 

 temperature of the month of January in the Konkan 

 coast districts is 76°, with a diurnal range of 20^. In the 

 Deccan {i.e. at Sholapur, &c.) and the Central Provinces 

 the mean temperature of the day in January is approxi- 

 mately 70°, and the diurnal range nearly 30^. In Bihar 

 the mean daily temperature of the month is 62°, and the 

 diurnal range 2"^. 



Mr. Eliot points out that since the air is very dry over 

 the interior, and the mean daily humidity percentages at 

 stations in the Deccan, Central Provinces, and Berar 

 averages about 40", any instruments brought out from 

 Europe, such as photographic cameras, &c., should be 

 constructed to withstand the action of this great dryness 



