Sept. 4, 1879] 



NATURE 



441 



press ; and part of the MS. for the fifth volume (for 1878) is in 

 hand. The average size of the three published volumes is 440 

 pages, each volume recording over 2,000 papers, &c. 



Fifticnth Riporl of the CominitUe for Exploring Kent' s Cavern, 

 Druomhire. Drawn up by W. Pengelly, F.R.S. — Work during 

 the pa-st year has been carried on in the "High Chamber" and 

 its branches. This chamber extends for about 53 feet in a north- 

 westerly direction from the "Cave of Inscriptions." At its inner 

 or north-western end it sends off two branches ; the northern 

 branch was excavated for about 12 feet, when the work was 

 abandoned, as breccia, blocks of limestone, and crystalline 

 stalagmite reached the roof and rendered further progress difficult 

 and expensive. The " High Chamber " contains only breccia, 

 the oldest mechanical deposit in the cavern, and the crystalline 

 stalagmite which overlies it. Bones of bears and implements 

 have been found in the breccia here, and some recent objects 

 were found on or near the surface. The southern branch of the 

 High Chamber is called the " Swallow Gallery," from a swallow- 

 hole which occurs about 18 feet from the entrance. This has 

 been explored for about 50 feet. It alsocontains only breccia, 

 generally lying bare, but covered with crystalline stalagmite at 

 the inner part of the chamber. Here too the remains consist 

 chiefly of bear ; a few implements have also been found. There 

 were entrances to the cavern by the Swallow Gallery and through 

 the swallow holes ; but these were quite closed before the 

 beginning of the "cave-earth era," and have since remained so. 

 Excavations have also been made in Clinnick's Gallery; but 

 here, as in former years, the number of " finds" has been small. 



Prof. A. Leith Adams has availed himself of the collection of 

 mammoth remains made during several years from Kent's 

 Cavern, to illustrate his memoir for the Paljeontological Society 

 on "British Fossil Elephants." Extracts from this memoir are 

 given in the report, and especial mention is made of a molar 

 found in 1874 in the "Cave of Rodentia." Prof. Adams says : — 

 "This tooth is one of the smallest milk-molars of any elephant 

 with which I am acquainted, and is even more diminutive than 

 the first milk-teeth of the Maltese pigmy elephants." 



Report on the Miocene Flora, &'e., of the North of Ireland, by 

 W. H. Baily. — The plants occur, between two beds of basalt, in 

 a deposit of brown and red bole, and immediately overlying a 

 bed of pisolitic iron ore, which has been extensively worked. 

 Twenty-five species of plants have been determined ; they are 

 most closely allied to the fossil flora of North Greenland, some 

 of the forms also occiu'rirg at Bovey Tracy. 



Sixth Report of a Committee consisting of Professors Herschel 

 and Lebour, and Mr. J. T. Dunn, to determine tJie Thermal 

 Conductivities of certain Rocks, showing especially the Geological 

 Aspects of the Investigation. — The research and correspt ndence 

 which it would require to complete a historical sketch of the 

 attempts already made to determine by experiments the thermal 

 conductivities of the most widely distributed terrestrial rocks, 

 which the Committee proposed to prepare during the past year, 

 are not so far advanced at present as to allow them to be com- 

 prehended in this year's Report. But the Committee hopes 

 during the coming year by continuing its inquiries with the 

 addition to its numbers of the names of Professors W. E. Ayrton 

 and J. Perry, of the Imperial College of Engineering in Japan, to 

 carry out the object of its undertaking, so as to exhibit the state 

 of our knowledge of the data of thermal conductivity of those 

 widespread kinds of rock which constitute the external materials 

 of the globe. 



The Committee has obtained during the past year some mea- 

 surements of thermal conductivities both of rocks and ebonite, 

 and india-rubber, and corroborates the very low value found by 

 Prof. Stefan, of Vienna, for the conductivity of ebonite. It has 

 also corrected some imperfections of its former tables, by show- 

 ing that the values given in them have throughout been described 

 too low, by about an eighth of their assigned values, and find 

 that with this correction their results have been in close accord- 

 ance with the measures that Sir William Thomson and ether 

 observers deduced of the conductivities of soils and rocks in 

 places where underground thermometers have been sunk and 

 read regularly for many years. The records of such thermo- 

 meters m the grounds of the Royal Observatory at Greenwich 

 have been preserved continuously for more than thirty years, 

 and the last volume of "Greenwich Meteorological Reductions" 

 contains the observations of their temperatures for twenty-seven 

 successive year.-, 1847-73. '^^ record (ahready used in part by 

 Prof. Everett) might now afford a new and very valuable deter- 



mination of the conductivity of sand and gravel strata, such as 

 make up the materials of Greenwich Hill, upon which the Royal 

 Observatory is placed. 



Report of the Committee, consisting of Prof . Sir William Thorn, 

 son. Prof. Clerk-Maxwell, Prof. Tail, Dr. C. W. Siemens, Mr. 

 F. J. Bramwell, and Mr. J. T. Bottomley for commencing Secular 

 Experiments upon the Elasticity of Wires, by J. T. Bottomley. — 

 At the last meeting of the British Association, the arrangements 

 for suspending wires for secular experiments in the tube which 

 has been erected in the tower of the Glasgow University Build- 

 ings, and for observing these wires, were described and reported 

 as complete. Some improvements have since been found 

 necessary ; but, so far as these are concerned, there is not much 

 to add to the report then given. 



The long iron tube has been closed at the top and bottom so 

 as to keep out currents of air and dust, and the joints of the 

 tube have been carefully caulked. 



Some improvements in the cathetometer used for observing 

 the marks on the wires were also found to be required, but the 

 instniment is now satisfactory. 



Six wires have now been suspended in the tube ; their stretch- 

 ing weights have been attached to them, and they have been 

 carefully marked and measured. These wires are suspended in 

 pairs — two of gold, two of platinum, and two of palladium. 

 One of each of the pairs is loaded with a weight equal to one- 

 twentieth of its breaking weight, and the other of each pair 

 with a weight equal to one-half of its breaking weight. The 

 points of suspension for each pair are very close together, so 

 that any yielding of the place of support affects both wires 

 equally. 



Each wire is marked with paint marks, and there are other 

 marks on the wires and on the weights attached to them where 

 positions have been determined. These marks are described in 

 a laboratory book which is »t present kept in the room of the 

 professor of natural philosophy in the University of Glasgow. 

 The measurements that have been made, and the experiments 

 that have been undertaken in connection with the work assigned 

 to the Committee, are all being entered in this book. This, 

 however, can only be regarded as a temporary mode of keeping 

 these records. 



It is intended that the record in this book shall contain — 



1. Description of the tube and arrangements for suspending 

 the wires, and for suspending additional wires at future times, and 

 description of the mode of attachment of the stretching weights. 



2. Description of the cathetometer and method of measuring 

 the changes, should there be any, in the lengths of the wires. 



3. Description of the wires themselves, and record of experi- 

 ments that have already been made on them as to breaking weight 

 and Young's modulus of elasticity. 



4. Description of the marks put on the wires, and record 06 

 the measurements that have been made as to the lengths of the 

 wires and as to the relative positions of the marks at the time of 

 suspending the wires. 



The stretching weight and the clamps attached to the wires are 

 engraved each with the amount of its weight in grammes. The 

 measurements are all made in grammes and centimetres. 



It seems desirable, considering the nature of the experiments 

 that are just now commencing, that information regarding them 

 should be preserved to the British Association in some appro- 

 priate way ; and that provision should be made for recording 

 every change that may take place, and for communicating from 

 time to time to the Association such information as may be 

 obtained. 



In the report presented to the Association by this Committee 

 last year, it was mentioned that experiments had been com- 

 menced in the laboratory of the University of Glasgow in 

 connection with the present investigation on the effects of stress 

 maintained for a considerable time in altering the elastic pro- 

 perties of varions wires. These experiments are still being 

 carried on, and results of interest and importance have been 

 already arrived at. 



The most important of these experiments form a series that 

 have been made on the elastic properties of very soft iron wire. 

 The wire used was drawn for the purpose, and is extremely soft 

 and very uniform. It is about No. 20 B.W.G., and its breaking 

 weight, tested in the ordinary way, is about 45 lbs. This wire 

 has been hung up in lengths of about 20 feet, and broken by 

 weights applied, the breaking being performed more or less 

 slowly. 



