June 22, 1882] 



NA TURE 



191 



wire -15 millirn, diameter, and about 432 ohms resistance, attached 

 to an insulated cable by which it can be lowered to the required 

 depth, and connected so as to form one arm of a Wheatstone s 

 bridge. The corresponding arm of the bridge is formed by a 

 second'coil made precisely similar to the former one and of equal 

 resistance. This coil is immersed in a copper vessel filled with 

 water, and the temperature of the water i, adjusted by adding 

 iced or hot water until the bridge is balanced. The temperature 

 of the water in the vessel is then read by a mercurial ther- 

 mometer, and this will also be the temperature of the resistance 

 coil. 



To avoid the error, which would be otherwise introduced by 

 the leads of the resistance coil, the cable was constructed of a 

 double core of insulated copper wire, protected by twisted gal- 

 vanised steel wire. One of the copper cores was connected to 

 each arm of the bridge, and the steel wire served as the return 

 earth connection for both. 



Sir \V. Thomson's marine galvanometer with a mirror and 

 scale was employed to determine the balance of the bridge. 



Mr. J. E. Hilgard, assistant in charge of the United States 

 Coast and Geodetic Survey, has sent me the results of Com- 

 mander Bartlett's experiments. The apparatus was set up on 

 board the Blake in April, 1881, and experiments were made off 

 the east coast during August. In each series of experiments 

 the temperatures at different depths were first taken by Miller- 

 Casella thermometers attached to a sounding wire. A sinker 

 was then fastened to the resistance coil, and it was lowered by 

 the cable to the same depths, and the temperature read by means 

 of the mercurial thermometer attached to the comparison coil. 

 The depths at which readings were taken ranged from the sur- 

 face down to 800 fathoms, and experiments were made both in 

 rough and still water. The temperatures recorded varied from 

 38'5* to 81 "5° F. In every case the readings of the electrical 

 instrument were precisely the same as those of the Miller. Casella 

 thermometers for the surface and the maximum depth ; but for 

 intermediate positions it was observed that the electrical thermo- 

 meter in almost every case gave a slightly higher reading. This 

 discrepancy may be accounted for, I think, by the circumstance 

 that the electrical thermometer gives the temperature of the 

 water actually surrounding the coil at the moment of observa- 

 tion, whereas the Miller-Casella instrument brings to the surface, 

 or at least its readings are effected by, the maximum or minimum 

 temperatures encountered in its ascent or descent, which may 

 not coincide with that at the point of stoppage. This furnishes 

 a very strong argument in favour of the superior accuracy of the 

 electrical instrument. 



It was found that about five minutes must be allowed at 

 each observation for the resistance coil to assume the temperature 

 of the water surrounding it, and a second period of five minutes 

 for adjusting the temperature of the comparison coil on deck. 

 Allowing five minutes more for lowering the cable, fifteen 

 minutes sufficed to complete a deep sea observation. 



Chemical Society, June I. — Dr. Gilbert, president, in the 

 chair. — The following papers were read : — Determination of 

 nitric acid in soils, by R. Warington. The sample should be 

 taken in dry weather from the subsoil, as well as from the sur- 

 face. It is dried at 55° C, and powdered. About 200 to 500 

 grms. are extracted in a vacuum filter with about 100 c.c. of 

 water ; the extraction requires ten to forty-five minutes. The 

 nitric acid is determined by a modification of Schlcessing's 

 method, the nitric oxide gas obtained being measured. — On a 

 spectroscopic study of chlorophyll, by Dr. Russell and Mr. 

 Lapraick. The authors have not endeavoured to isolate a pure 

 substance, but have endeavoured to follow spectroscopically the 

 changes of a body (or bodies) which gives a particular absorp- 

 tion spectrum. This chlorophyll was extracted by a mixture of 

 alcohol and ether, and gives the well-known absorption spectrum 

 of four bands easily seen, and three other bands in the violet 

 end, which are not noticed with gaslight. This chlorophyll, 

 by treatment either with a small quantity of almost any acid, or 

 with some salts, as ferric chloride, mercuric chloride, &c. , or by 

 heat, is changed, and gives another characteristic spectrum, to 

 which the authors gave the laboratory name of "half-acid" 

 chlorophyll ; by the action of strong hydrochloric acid, a further 

 change is produced, and an absorption spectrum is obtained, 

 which is named " acid " chlorophyll. Alkalies act on chloro- 

 phyll, and give eventually an absorption spectrum of one broad 

 band in the red. Very concentrated caustic potash solution 

 splits this band into two bands, one of which ultimately dis- 



appears. The eye observations and measurements were checked 

 with photographs taken by Capt. Abney. All leaves gave 

 similar results, except some acid leaves, from the vine, &c, 

 which gave half-acid chlorophyll instead of the normal product, 

 when extracted with alcohol and ether. 



Zoological Society, June 6.— Prof. W. II. Flower, F.R.S., 

 president, in the chair. — The Secretary called the attention of 

 the meeting to the curious way in which the young Cormorants 

 lately hatched in the Gardens were fed by the parent birds, and 

 exhibited a drawing by Mrs. Hugh Blackburn illustrating this 

 subject. — A communication was read from Prof. St. George 

 Mivart, F. R.S., containing a series of observations on certain 

 points in the anatomy of the Cat-tribe (sEluroidea). — Mr. 

 Howard Saunders read a paper on some Larida collected by 

 Capt. H. H. Markham, R.N., on the coasts of Peru and Chili; 

 comprising, amongst other rarities, the third known example of 

 the large Fork-tailed Gull (Xema furcatum), a species which 

 had been vainly sought for on the Pacific coast of America for 

 upwards of thirty years. The author drew attention to the 

 peculiarities distinguishing the various species of gulls found in 

 the Pacific from those of the rest of the globe, and pointed out 

 that, owing to oceanic currents, the connection between the 

 species now only found on opposite sides of the equator had 

 evidently been much more recent in the Pacific than in the 

 Atlantic. — Prof. F. Jeffrey Bell read a paper containing an 

 attempt to apply a method of formulation to the species of the 

 Comatulida, and added the description of a new species, which 

 he proposed to call Actinometra annulata. — Mr. Francis Day, 

 F.Z.S., read some notes on the supposed identity of a specimen 

 of a fish determined by Dr. Gunther as Anguilla kieneri with a 

 Gadoid Lycodes. — Mr. E. J. Miers read the second portion of 

 his paper on the crustaceans received by the British Museum 

 frem the Mauritius, and called special attention to what appeared 

 to be a variety of Palinurus longimanus of the West Indies 

 which occurred in it. — Mr. W. A. Forbes read the fifth of his 

 series of papers on the anatomy of Passerine birds. The present 

 communication was devoted to the consideration of the structure 

 of the genus Orthonyx, which was shown to be a true Oscinine 

 farm. — Mr. H. J. Flwes exhibited and made remarks on a 

 Stonechat (Saxieola) which he had obtained during a recent 

 expedition to the Aures Mountains of Algeria. — The Secretary 

 exhibited a series of the diurnal and nocturnal lepidopterous 

 insects bred in the Insect' House in the Gardens during the 

 present season. 



Royal Horticultural Society, May 23. — Sir J. D. Hooker in 

 the chair. — Foliage injured by salt in the late gale : — Dr. Church 

 described experiments he had made at Cirencester during the last 

 fifteen years to a> certain the amount of salt in the rain brought by 

 autumnal gales, especially from the south-west. He found from 5 

 to 7 grs. per gallon, while the ordinary amount was only - 5 grs. 

 The average winter amount was but slightly in excess of the 

 average summer quantity. He noticed that in Oakley Park, 

 one side of the trees was severely injured, a*d that, if no rain 

 followed for a few days after the yale, the salt sparkled on the 

 trees, even at a distance of thirty-five miles from the sea. The 

 salt abstracted the moisture from the leaf-cells, and formed a 

 condensed solution, so that the leaf became completely dried np, 

 and perished. Mr. McLachlan added that salt had been ob- 

 served on windows at Lewisham, as at Croydon, and elsewhere. 

 Sir J. D. Hooker remarked that Dalton was the first to recerd 

 a similar observation at the beginning of this century. With 

 regard to beeches withstanding the gale better than oaks, as men- 

 tioned at the last meeting, it was elicited that they were unhurt 

 at Kew, and Valewood, Haslemere, but at Cirencester, in Dorset- 

 shire, and Cornwall, they suffered severely. Mr. Blackmoor 

 exhibited foliage of pears, &c, from Teddington, some of which 

 was quite unhurt ; of other trees growing adjacent to them, the 

 leaves were much injured. Vines and peaches showid similar 

 differences. He suggested that it could not be salt in this case. 

 The opinion generally entertained was that such discrimination 

 were due to the trees being of relatively hardy and less hardy 

 kinds. — Rhododendron trijlorum : Mr. Mangles exhibited sprays 

 of this species from the Himalayas. It belongs to the scaly- 

 leafed section, and he observed that members of this group will 

 not hybridise with any species of rhododendron without scales on 

 the foliage. — Malformed tulip : Mr. Smee exhibited a tulip 

 having petals distributed down the peduncle, a nut uncommon 

 occurrence. Mr. Henslow remarked on the fact that when such 

 a petal was half-green and half-coloured, the tendency of the 



