October 7, 1915] 



NATURE 



155 



theoretical resolving power in the sixth order is 

 660,000, and 600,000 has actually been attained on a 

 negative from which was prepared the illustration 

 accompanying the paper. 



The Solar Physics Observatory, Cambridge. — We 

 have received a copy of the second annual report of 

 the director relating to the year April i, 1914, to 

 March 31, 19 15. Disadvantageous conditions arising 

 out of the war have imposed serious limitations on 

 the output of work, and have also retarded the in- 

 stallation of equipment. Mr. Baxandall has made 

 considerable progress in working out the details of 

 the chemistry stellar spectra for the projected atlas. 

 The green regions of the spectra of a Cygni, a Canis 

 Minoris, a Persei, and a Canis Majoris have been 

 reduced, and the results are being prepared for 

 pubUcation. Spectra of several bright stars have been 

 photographed in the course of adjusting the new 

 spectrograph used with the 15-in. Huggin's refractor. 

 Solar work has evidently been prosecuted both with 

 zeal and success. The observers with the South 

 Kensington spectroheliograph are especially to be 

 congratulated on having secured spectroheliograms of 

 the sun's limb on no fewer than no days. The solar 

 eclipse expedition to Theodosia in the Crimea was 

 very unfortunately foiled by clouds, and this is doubly 

 regrettable as the eclipse provided some novel spectro- 

 scopic features. Successful photographs of sun-spot 

 spectra have been secured with the McCIean solar 

 instruments. In the laboratory a powerful spectro- 

 graph of the Littrow type has been improvised, using 

 a 6-in. plane grating and a 6-in. Cooke photovisual 

 lens, and thus the 21-ft. concave grating detained at 

 Odessa will scarcely be missed. 



LONG-DISTANCE WIRELESS 

 TELEPHONY. 



THE announcement that the United States Navy De- 

 partment has successfully experimented with a 

 wireless telephone from Arlington, Virginia, to Mare 

 Island, California, is chiefly interesting on account of 

 the distance covered — 2500 miles. If this success can 

 be maintained in all conditions it will mark a notable 

 achievement and one upon which the naval authorities 

 in the United States may be complimented, because of 

 the many years of steady and silent work which they 

 have devoted to the subject. 



There is nothing inherently imjxjssible in long- 

 distance wireless telephony, and from the scien- 

 tific point of view there is no reason why 

 it should not be carried on over even greater 

 distances than that recorded above, but there are prac- 

 tical difficulties in regard to the construction of a 

 microphone transmitter capable of passing large high- 

 frequency currents, and in the production of the neces- 

 sary persistent oscillations. In ordinary telephony, the 

 current going through the microphone is quite small, 

 and so long as the power to be dealt with is small, it 

 is easily possible to obtain a microphone capable of 

 dealing with the amount of energy while giving good 

 articulation. But when a p)ower measured in kilo- 

 watts has to be dealt with it is another matter. By 

 using many microphones in parallel ; by cooling the 

 carbon granules with gas or immersing them in oil, 

 and a host of similar devices, inventors have sought to 

 produce one capable of dealing for protracted periods 

 with a heavy current; but either they have not- been 

 entirely successful in this, or articulation has suffered. 

 It is therefore desirable to await a full official account 

 of the experiments carried out by the United States 

 Navy Department before expressing an opinion upon 

 the results. This is all the more necessnrv because 



of the great difficulty of judging the success of long- i 

 distance and other experiments merely by "reading." 



It is extraordinary, in practice, to observe the marked ; 

 difference between ' the distance at which speech is 



audible and the distance to which it is truly intelligible. " 

 The faint overtones and small nuances upon which 

 intelligible speech depends are, at best, all too lightly 

 impressed on the ever-varying curve of intensity sent 



out; and if they are smothered up or glossed over by : 



/a coarse microphone, a distant receiving station where ; 

 the signals are weak gets only the bare fundamental 



tones stripped of all meaning. It is very easy to be ' 

 deceived in this, and when well-known words are 



uttered, the ear glibly supplies the missing sounds. 1 



EXPERIMENTS ON HOMING.^ \ 



PROF. J. B. WATSON and Dr. K. S. Lashley ] 



have made some important experiments at Bird ; 



Key, in the Ibrtugas, on the homing capacity of the 1 

 noddy tern {Anous stolidus) and the sooty tern (Sterna 



juligtnosa), which breed there in large numbers. The , 

 island is peculiarly suitable for the purpose, since it 

 marks the northern limit of the migration of these 



two tropical terns (so that if the birds are experi- 1 



mentally transported further north they find themselves i 



in regions which they have not previously visited); ^ 



moreover, on the westward side there is only the open ] 

 water of the Gulf of Mexico until the shore-line of Texas 



is reached, Galveston being 855 statute miles distant. \ 



I "This strip of open water proves a magnificent route ' 



for homing exf>eriments." The authors caught terns \ 



at their nesting-places, put individual marks of paint ■ 

 on their head and neck, tied a small tag recording 



the date, locality, and marking round the neck, fixed : 



a larger duplicate tag beside the nest, transported the ] 

 birds in large cages to a distance, liberated them, and 



watched for their return. The general result is of i 



great interest: — "The noddy and sooty terns can j 



return from distances up to 1000 miles in the absence ^ 



of all landmarks, at least so far as the term landmark ^ 



is understood at present." \ 



Some details of this careful piece of work may be I 

 I noted, for they are very instructive. From Galveston 

 I (855 miles away) three birds returned out of ten, 



! taking from about six to about twelve days ; two noddies ■ 



liberated at 720 miles both returned, taking between \ 



eleven and seventeen days ; out of ten birds liberated i 



at 585 miles eight returned, taking from about four to j 



about eight days ; out of four noddies and four ; 



sooties liberated in open water 461 statute miles away, \ 



two noddies returned in three days ; of twelve taken north \ 

 to Mobile, only one returned, taking about seven days ; 



two noddies and two sooties carried in a state-room to \ 

 Havana and released in the harbour there early in 



the morning of July 11, returned to Bird Key on the ' 



i2th, the distance in a straight line being about ■ 



108 statute miles; of three noddies and two sooties : 



liberated off Cape Hattcras (850 miles to the north), \ 



both of the latter and at least one of the former species j 



returned after several days. "The alongshore route, ■ 



which is the one in all probability chosen by the birds ] 



on their return, since they were gone several nights, \ 

 is approximately 1081 statute miles." (It seems that 



the birds almost never rest on the water, unless they ) 



happen to find pieces of driftwood or the like.) The I 



records show that the terns often take as long for ' 



short distances as for long distances, and that a return \ 



from the open sea outside of all landmarks is just as 1 



practicable as a return from a coast. ■ 



By a series of exceedingly careful experiments Dr. i 



1 P.-jp-rs from the T)ep«rtii)^nt of Marine Bio'ogy nf the Carneei' Insti- 



Mition at Wishineton. Vol. vii., " Homing and R^latrd Activities of Birds." ^ 



By r. H. VVai'on „n\ K. S. l.asMey. Pp. i-i044-7 plates-t-g figs. (Wash- \ 



ington : The Carnegie Institution, 1915.) I 



NO. 2397, VOL. 96] 



