Dec. 1 6, 1875] 



NATURE 



139 



which are definite functions of z, Xj . . . *■„ ; and when these 

 conditions are satisfied to determine the solution. Three cases 

 arise for discussion : (i) « - i of the arguments independent, 

 (2) n of them independent, (3) « + i of them independent 

 The paper concludes with a note on the application of a similar 

 method to equations of an order higher than the second. 



Zoological Society, Dec. 7. — Mr. George Busk, F.R.S., 

 V. P., in the Chair. — Mr. Sclater read an extract from a letter 

 addressed to him by Mr. H. A. Wickham, on the occurrence of 

 the large blue Hyacinth Macaw, {Ara hyacitithina) near San- 

 tarem, on the river Amazons. —Mr. Sclater exhibited and made 

 remarks on a Skin of Hyfocolius ampdinus., Bp, obtained by Mr. 

 \V. T. Blanford, in Upper Scinde, to the west of Shikaprur. 

 — Prof. Owen, C.B., read the twenty-second part of his series 

 of Memoirs on Dinomis. This part contained a restoration of 

 the skeleton of Dinornis maximus. — Mr. J. Vv. Clark read a 

 paper on the Eared Seals of the islands of St. Paul and Amster- 

 dam, to which he added a description of the Fur Seal of New 

 Zealand from specimens kindly furnished by Dr. Hector. Mr. 

 Clark further read copious extracts from the narratives of the 

 older Explorers in these seas, and attempted to reconcile the 

 notices given by them with the subsequent description of 

 Naturalists. — A communication was read from the Rev. R. 

 Boog Watson, on the generic peculiarities of the distinctively 

 Madeiran Achatinas of Lowe.— A communication was read 

 from Dr. Hermann Burmeister, Director of the National 

 Museum, Buenos AjTes, containing the description of a new 

 species of Dolichotis—yiicic^a Dr. Burmeister proposed to call 

 Dolichoth salinicola.—'Sh. W. T. Blanford communicated par- 

 ticulars respecting some large Stags' Horns, obtained by the 

 Expedition to Western Turkestan to which the late Dr. Stoliczka 

 was attached as Naturalist, said to have been brought originally 

 from the Thian Shan Mountains. These horns were of very 

 large size, each measuring 51 inches in length round the cmrve- 

 Mr. Blanford, considering that these horns clearly showed 

 the existence of a species hitheito undescribed, gave a full 

 description of them, and proposed to give the name of Cervus 

 eusiephanus to the animal to which they belong. — Dr. O, 

 Finsch communicated some notes on Fhanuomams iora, Shaip, 

 and Abrornis airicapilla, Blyth, and pointed out that the first 

 named bird is identical with lora lafresnayei of Malacca, while 

 Abrornis atricapilla, said to be from China, is in fact a MyiodiocUs 

 pusUlus, Wils., a well known North American bird. — A second 

 communication from Dr. Finsch contained the description of a 

 bird from the Arfak Mountains, New Guinea, which appears to 

 form a new genus and species. This Dr. Finsch proposed to call 

 Pristornamphus versteri. — A third communication from Dr. 

 Finsch gave the characters of six new Polynesian birds in the 

 Museum Godeffroy at Hamburg. — A communication from Mr. 

 J. Caldwell, contained some notes on the Zoology of the Island 

 of Rodriguez. — Dr. E. Von Martens communicated a list of the 

 Land and Fresh Water Shells collected by Mr. Osbert Salvia in 

 Guatemala in 1873-74. 



Geological Society, Dec. I. — Mr. John Evans, V.P.R.S., pre- 

 sident, in the chair. — ^L Rodolfo de Arteaga, William Henry 

 Barnard, the Rev, J. Clifford, M.A., Lieut.-Gen. Robert Fitz- 

 gerald Copland-Crawford, R.A., Walter Derham, B.A., James 

 Duigan, George R. Godson, the Rev. Algernon Sydney Gren- 

 fell. Sir David Salomons, Bart., Aubrey Straian, B.A., 

 William Thomas, Edward Wethered, F.C.S., the Rev. Burgess 

 Wilkinson, and Edward Alfred Wiinsch were elected Fellows of 

 the Society. The following communication was read : — On the 

 granitic, granitoid, and associated metamorphic rocks of the 

 lake-district.— Parts III., IV., and V., by Mr. J. Chfton Ward, 

 of the Geological Survey of England and Wales. Part IIL On 

 the skiddaw granite and its associated metamorphic rocks. The 

 subject was treated under the three heads of (1) Examination in 

 the field, (2) Microscopical examination, (3) Chemical examina- 

 tion, and the following were the general results arrived at The 

 metamorphism of the skiddaw slate extends for many miles 

 aroimd the several granitic masses, and commences by the for- 

 mation of small spots which become developed into chiastolite 

 crystals. The chiastolite slate passes into spotted schist, by the 

 great increase of the small oblong spots arranged aioi^g planes of 

 foliation, and mica appears. The spotted schist graduates into 

 mica -schist, which, however, often retains to the last faint spots, 

 and occasionally chiastolite crystals. The junction between the 

 mica-schist and the granite is generally rather abrupt On the whole, 

 chemical and field evidence esj)ecially zit^-' against regarding the 

 r:T3nite, now exposed, as the result of the extreme metamorphism 



of the skiddaw slates imnudiately arotmd it ; but whether it may 

 not have resulted from the metamorphism of underlying parts of 

 the same series is an open question. The great contortion of the 

 mica schist around the granitic centres may be in part due to the, 

 at any nx^, partially intrusive character of the granite. In an 

 appendix abstracts of papers by various authors who have written 

 in connection with the subject were given. — Part IV. On the 

 quartz felsite, syeniric, and associated metamorphic rocks of the 

 lake district This part was treated imder the same three heads 

 of field, microscopical, and chemical evidence as the last The 

 quartz felsite of St John's Vale, and the syenitic granite of 

 Buttermere and Ennerdale, lie for the most part at the junction 

 of the volcanic and skiddaw series, and seem by their line of 

 strike, and by the occasional presence of bands of slate or 

 volcanic rock enclosed within or miming through them, to 

 represent the transition beds between the two series, metamor- 

 phosed in great measure in situ. Both microscopic and chemical 

 evidence demonstrate the possibility of this process. Evidence 

 gathered in the field, and microscopic and chemical examina- 

 tion, all seem to suggest that the rocks of Carrock Fell, &c, re- 

 present the base of the volcanic series, consisting largely of con- 

 temporaneous traps, thrown into a synclinal, the axis of which 

 ranges generally east and west, and metamorphosed into rocks 

 of greatly varying character, such as sphaerolitic felsite, hypers- 

 thenite, and diorite. Although all the various masses treated of 

 were probably formed in the main by the metamorphism of beds 

 in situ, it is probable that some parts of the resulting magma 

 became occasionally intrusive among and absorptive of higher 

 beds. In an appendix notices of papers on these rocks by other 

 authors were given. — Part V. General stmimary. In this part 

 the leading results of the four preceding divisions of this memoir 

 were briefly brought forward, followed by the discussion of 

 various considerations relating to metamorphism, imder the fol- 

 lowing heads: — l. Granite at various depths; 2. How far 

 granite may be an ultimate universal product of metamorphism ; 



3. Distribution of metamorphism (selective metamorphism) ; 



4. Classes of metamorphism. The paper was illustrated by a 

 large geological map of the northern part of the Lake district, 

 by a geolc^cal model of the Keswick district, by rock specimens, 

 and large coloured photographs taken from water-colour micro- 

 scopic drawings made by the author. 



Physical Society, Dec. 11. — Prof. Gladstone, F.R.S., pre- 

 sident, in the chair. — The following candidates were elected 

 members of the Society :— C. Higgins and S. O. Thompson, 

 B.A., B.Sc. — In the absence of Prof. G. C. Foster, Mr. Lodge 

 exhibited and described a simple form of chronoscope for mea- 

 suring short intervals of time, which Prof. Foster has recently 

 devised. In experiments commenced about eight years ago the 

 apparatus consisted essentially of three parts : l. An arrange- 

 ment for releasing the bullet or other body whose fall vras to be 

 timed, when the apparatus is employed for such determinations ; 



2. An arrangement for directing a gauged stream of water into a 

 vessel during the time occupied by the fall of the body ; and 



3. A platform to receive the falling body. The stream of water 

 was directed into the vessel by means of a bent fimnel brought 

 under a constantly flowing stream by an electro-magnet. But 

 this apparatus had two serious defects, one of which was caused 

 by the diflSculty of accurately gauging the stream, and the other 

 by the inertia and consequent sluggishness of movement of the 

 funnel. The arrangements, however, for dropping and receiving 

 the bullet being satisfactory, were finally adopted. The former 

 is simply a clip one side of which is a spring, and this forms the 

 armature of a small electro-magnet. On completing the circuit 

 the spring is drawn aside and the bullet released, momentarily 

 breaking a current which passes through it, as subsequaitly 

 described. The bullet, at the end of its fall, strikes a 

 small mahogany table, so arranged that the blow slightly 

 depresses it, and permanently breaks the same current, 

 which in the interval has been closed by a subsidiary 

 wire. The author abandoned the method of indicating 

 the commencement and end of the fall by an independent 

 electro-magnet and, substituting the trace made on blackened 

 paper by a vibrating tuning-fork for the stream of water, he 

 registered them by perforations made by induction-coil sparks in 

 the blackened paper, a method suggested by the description of 

 Beetz chronoscope. The apparatus is difficult to describe ^v^lh- 

 out the aid of diagrams, but the following wiU perhaps suffi- 

 cienUy indicate the general arrangement. The two terminals of 

 the secondary coil are connected, the one with the tuning-fork, 

 and the other with the metallic drum on which the blackened 



