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Aviation History
1925
1925 - 0086.PDF
FEBRUARY 12, 1925 CORRESPONDENCE The Editor does not hold himself responsible for opinions expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters intended for insertion in these columns. THE RECENT CATASTROPHE AT CROYDON[2088] Is it possible that the capillarity effect generally called the " Jamin effect " may have some bearing upon the recentcatastrophe at Croydon ? Jamin discovered, many years ago, that a " chaplet ofdrops," that is to say, a series of air bubbles separated by water drops within a capillary tube, required a very greatpressure to shift it along the tube. This phenomenon is explained in Poynting and Thomson's " Properties of Matter,"on p. 142 of the 1913 edition (Griffin and Co.). In 1919, on the occasion of the aeroplane catastrophe onthe coast of Ireland, I made a few experiments in order to discover whether possibly a chain of water drops in a tubecontaining petrol might exhibit the same effect, and I found by preliminary experiments that the effect was considerable,a chain of 18 drops of water in a glass tube of 2 mm. bore, containing No. 1 Shell petrol, supporting a head of 14 cm. ofpetrol. I have not been able to continue the experiments, but wouldsuggest that a wide range of such experiments might disclose some important facts bearing upon the unexplained stoppageof flow in petrol supply pipes. The material of the inner walls of the pipe must affect the forces greatly, and possibly in agut-lined pipe the effect may be so greatly enhanced as to become important in tubes of considerable bore. It is not easy to introduce a chain of drops, but the presenceof a filter of fine gauze on which drops of water can collect must,* I think, facilitate the process under certain conditionsof vibration. F. M. DENTON, A.C.G.I., M.I.E.E.Arosa, Switzerland. February 3, 1925. ROYAL AERONAUTICAL SOCIETY (Official Notices)ON Thursday, February 19, a joint meeting of the Royal Aeronautical Society and theInstitution of Automobile Engineers will take place at the Society of Arts at 7 p.m.,on which occasion light refreshments will be provided at 6.30 p.m. The subject ofthe paper will be " Light Aeroplane Engine Development," by Lieut.-Col.L. F. R. Fell, D.S.O..O.B.E." It is regretted that Colonel FrankSearle has found it necessary to postpone his lecture on " The Maintenance of Commercial Aircraft," which had beenarranged for February 12. \V. LOCKWOOD MARSH, Secretary * m m m South African Air MailsTHE Postmaster-General announces that, beginning on Friday, February 13, and on each Friday thereafter untilfurther notice, a new letter Air Mail will be despatched from this country by Union Castle Packet, for onward conveyancefrom Capetown by the experimental Air Mail service which the Union Post Office is about to institute between that placeand Durban. The Mail aeroplane will be due to leave Cape- town each Monday, beginning on March 2, immediately afterthe arrival of the Packet, and to reach Durban the same day calling on the way at Mossel Bay, Port Elizabeth and EastLondon. It is to return from Durban (calling at the same points) in time to connect with the homeward Mail Packetsailing from Capetown each Friday. By the use of the Air Mail letters from this county for Mossel Bay, Port Elizabeth,East London and their respective districts, and for Durban and probably the whole of Natal, should be saved up toone or two days in time of transmission : and addressees in Durban should be afforded an interval from Tuesdayto Wednesday,- or to Thursday inclusive, in which to reply either by return ordinary, or by return Air Mail. Any letter intended for transmission by the Air Mail must bear in thetop left-hand corner of the cover the official blue Air Mail label (or be plainly marked in manuscript " By Air Mail "),and must be prepaid in postage stamps in the usual way with a special fee of 6d. per oz. in addition to the ordinary Imperialrate of postage. It may be posted, subject to observance of these conditions, in any of the ordinary ways of posting ;and it may be registered, but not insured. The latest times of posting (including late fee posting) for the new Air Mailwill be generally as advertised for the ordinary post to South Africa, but there will be no late fee posting in Londonat Waterloo Station on Fridays for the Air Mail. Late fee letters must be prepaid with the appropriate late fee,in addition to the Air Mail fee. "Wakefield" Scholarships and " Hyde- Thomson "Memorial Prize THE Air Ministry announces that the " Wakefield "Scholarships amounting to ^75 each have been awarded to Flight Cadets John Clarke and R. J. Drummond-Brown,and the " Hyde-Thomson " Memorial Prize, amounting to about ^32, has been won by Flight Cadet C. W. Cooper.Flight Cadet Clarke obtained the first place among the aircraft apprentices recently selected for cadetships oncompletion of their three years' training at the School of Technical Training, Halton. Flight Cadet Drummond-Brown obtained the 8th place at the competitive examina- tion held in November last for entry into the Royal AirForce Cadet College, Cranwell, and the first place on the list of candidates for the " Wakefield " Scholarship. FlightCadet Cooper was the aircraft apprentice selected for a cadetship who passed out first on completion of his trainingat the Electrical and Wireless School, Flowerdown. It will be remembered that the " Wakefield " Scholarship wasinstituted in 1920 by Sir Chas. Wakefield, Bart., C.B.E. The " Hyde-Thomson " Memorial Prize was founded in 1919by Mr. R. D. Hyde-Thomson for the promotion of pro- ficiency in wireless telegraphy, in memory of his son, the lateLieut-Colonel Douglas Hyde-Thomson, R.A.F., who was killed whilst flying on duty. A "Franco-Roumaine" Souvenir : This hand- s o m e medallion is struck by the Cora pagnie Internationale de Navigation Aerienne in commemoration of the establishment of the air route between Paris, Prague, Vienna, Budapest, Bucharest, Constantinople Air Route. The machine depicted is obviously inspired by the Bleriot- Spad 33. 86
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