NATURE 



[January 4 



i'( 



VVb hav* rpr-ivfd nn inttreslinfj little booklet from th« 

 Silent Klrrtric Clmk Company, of 193 Go«wp1I Road, with 

 which it pmbw'i'd th»- firmV latent catalogup and pricf- 

 ti«it. Thi« iKMikIrt i« worthy of notice, for it differs widely 

 from tlie ordinary run of price-lists, inasmuch as it con- 

 tains a complete description of this firm's system, a 

 systein which is based iiix>n more than sixteen years* ex- 

 jwrirnre of a class of apparatus which the Silent 

 il.urii Clock Company has apparently brought to a 

 WDiiilcrful degree of perffi li.xi. iudfiiing from the list of 

 more than eighty recent 'Hs which have been 



supplied, no doubt much u-. : ;ii.>faction of the users, 



amongst which wc notice several British, colonial, and 

 foreign Government departments, home municipalities, 

 schools, and ra'lwny companies. It is interesting to 

 observe that every department of time-keeping is provided 

 for : large and small clocks ; turret clocks ; clocks for use 

 on shipboard, with automatic adjustments for diurnal 

 longitudinal correction ; clocks arranged to strike and chime 

 • l<>ctrically, both for tioii^rlmlc! as well as for public 

 iistallations ; and also tor rini^iii;^ Ixlls according to vari- 

 able programmes ; hinh-gmdo astronomical clocks, and 

 master clocks arranged for automatic synchronisation by 

 means of the daily signal distributed by the Post Office 

 Telegraph Department from Greenwich Observatory. Any 

 of our readers interested in electric clock systems should 

 certainly send an inquiry to this firm. 



DuRiNO the spring and summ. 1 of iqio the United States 

 Nnval Wireless Laboratory t.ini.d out an extensive series 

 >■! I \|i lini' ni- on the ranj4' of < uminunication by wireless 

 !■ li^iapiiy bitween two iiiiiN.ix and the Brant Rock 

 station, near Boston. An aiccumi of the work done and 

 the results obtained is given by Mr. L. W. .Austin in the 

 October (191 1) number of the Bulletin of the Bureau of 

 •Standards. The antenna of the Brant Rock station was 

 :-'o feet high, and of the umbrella type; those of the 

 > ruisers were 116 feet, and of the flat top type. In each 

 case the coupling between closed circuit and antennie was 

 loose rnouf^h to cause only one wav.' to be emitted. Over 

 salt wairi th, received ciiti. nis ai> proportional to the 

 sending lurrt-nts and to the product of the heights of 

 sending and receiving antenna; divided by their distance 

 apart and by the wave-length used. In addition, they are 

 subject to absorption, which in the daytime is expressed 

 by multiplying the above by e-*^, where d is the distance 

 and a a constant the value of which varies inverselv as 

 the square root of the wave-length. During the night the 

 absorption is too irregular to be • represented by any 

 formula. The above statenn ni> have been tested over the 

 following ranges : — sending ( urr- iits, 7 to 30 amperes ; 

 aiitemi.f lieights, 37 to 130 l. ■ t : wave-lengths, 300 to 3750 

 ni'tr-- : distances up to 1000 mil-. 



Engineering for December 29, 191 1, contains an illus- 

 trated description of a floating crane of exceptional size 

 which is now in use at the .Austrian Naval Dockyard, Pola, 

 on the Adriatic. The crane is designed to deal with the 

 heaviest weights in ship construction, and also, on an 

 emergency, to raise sunken submarines. According to the 

 specification, the crane had t<> Iv provided with two crabs, 

 each having a lifting capacity of uo tons, the crabs being 

 so designed that both could bt> u- d simultaneously, especi- 

 ally for the lifting of submerged loads, in which case the 

 rear crab has to work at a maximum distance of 5 feet 

 from a line corresponding with the front edge of the 

 pontoon, the front crab being close against it. Arrange- 

 ments are made whereby the submarine can be raised 

 sutTiciently out of the water for rescuing the crew through 

 NO. 2201, VOL. 88] 



the conning tower, when the necessary steps could be 

 taken with more lci<iure for salving the submarine itself. 

 The crane can be propelled afloat at a speed of about 

 3-4 knots. Under test, each crab was made to carry a load 

 of 150 tons, the rear crab being at a distance of 5 feet, and 

 the front crab at a distance of 47 feet 7 inches, from « lin* 

 corresponding with the front edge of the pontoon. 



In chapter xv-- '■' 'ms *' Study of Bird Flight "-~^. 



is now appearii in the pages of Flight — Dr. E. H. 



Hankin discuss--, om > .ium- of soaring flight. Two ancient 

 theories are examined and rejected, i.e. that the soaring 

 bird takes advantage of (i) ascending currents reflected 

 upward from the walls of high buildings, &c. ; (a) ascend- 

 ing currents or eddies caused by heat ; for the reason, in 

 the first instance, of personal observation to the contrary 

 in the case ot heavy birds, and, in the second, that soaring 

 can in some conditions be impossible in the presence of 

 heat eddies as w-H as in their absence, and vice versa. 

 " There is no <\ id. nc •• whatever," says Dr. Hankin, " in 

 favour ol the view that the energy of soaring flight is 

 derived from the kinetic energy of air in movement in- 

 dependently of the bird's wing." The conclusion drawn 

 is that the energy used in soaring is stored up in the air 

 in potential form, for which he coins the word "ergaer." 

 On the question of the composition and decomposition of 

 "ergaer," our author admits he knows nothing, but 

 defends his theory as entirely scientific, merely advancing 

 the opinion that " ergaer " is stored sun energy, and that 

 " the air under the wing of a soaring bird is undergoing a 

 change of the nature of a sort of continuous explosion." 

 Later in the development of the idea we are asked to 

 suppose a bird gliding into a patch of soarable air with its 

 wings at full camber. In these conditions, the " pull " 

 would no longer act at the centre of gravity and would no 

 longer be the momentum, but would change to the tractive 

 effect of soarable air on the cambered wing, and so would 

 act on a level with the wings. 



A COPY of the January issue of his catalogue of second- 

 hand instruments (No. 49) has been received from Mr. C. 

 Baker, 244 High Holborn, London. The list contains par- 

 ticulars of nearly 2000 items, the majority of which will 

 interest the astronomer and the microscopist. The instru- 

 ments are guaranteed to be in adjustment, and are for sale 

 or hire. 



The twenty-eighth annual issue of " The Year-book of 

 the Scientific and Learned Societies of Great Britain and 

 Ireland " has now been issued by Messrs. Charles Griffin 

 and Co., Ltd. This useful work of reference is a record, 

 compiled from official sources, of the work done in science, 

 literature, and art during the session 1910-11 by numerous 

 societies and Government institutions. It is to be regretted 

 that the summary of the proceedings of the British 

 •Association, given on pp. 10 to 23, refers to the Sheffield 

 meeting held in September, 19 10, and not to the Ports- 

 mouth meeting of last year. Since the whole of the titles of 

 papers, reports, &-c., presented at the Portsmouth meeting 

 were available before the middle of September last, we 

 suggest they might with advantage have been included, in 

 addition to those relating to the 19 10 meeting. 



Errata. — The paper on " Momentum in Evolution " 

 published in last week's Nature was by Prof. Dendy, and 

 not Denny, as printed on p. 301. — We are asked to state 

 that on p. 296, col. one, line ten, " a rubber ram " should 

 be "an iron ram." The former words were given in the 

 manuscript supplied to us, and were passed in proof 

 by our contributor. 



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