156 



NATURE 



[June 15, 1893 



irometer, when a high order of accuracy is unnecessary, with- 

 out the usual observation in sulphur vapour, which, in the 

 absence of special apparatus, is a troublesome operation. For 

 if the platinum is pure, it may be assumed that at absolute zero 

 the resistance vanishes, and thus a measure of the resistance 

 in steam and ice will allow of its constants being calculated. 



While making the observations mentioned in the previous 

 note the authors were led to suspect that the heating effect of 

 the small currents necessary to measure a resistance are of more 

 importance than is usually supposed. During their deter- 

 mination of the value of the mechanical equivalent of heat by 

 means of an electric current, they measured the temperature of 

 the bath containing the wire under experiment, at which the re- 

 sistance was the same, while the difference of potential at the 

 ends was increased from one to ten volts. Hence they were 

 able to calculate the change of resistance (SR), and the results 

 seem to show that 5R = aC- where a is a coefficient depending 

 on the nature of the surroundings. Thus, by determining the 

 re istance of .1 coil with two different electromotive forces, it 

 would be possible to find the value ofo, and hence calculate the 

 value of the resistance when C = o. 



The June number of the Journal of the Institution of Electri- 

 cal Engineers contains a long paper by Mr. A. T. Snell on the 

 distribution of power by alternate current motors. The paper 

 is followed by a full report of the discussion which it raised 

 when it was communicated to the Institution. 



According to \h^ Electrical Review Messrs. Cross and Mans- 

 field have recently contributed to the Massachusetts Institute 

 of Technology some farther experiments on the excursion of 

 the diaphragms of telephones. They find that on increasing 

 the magnetising current, the corresponding permanent deflection 

 increases more and more rapidly in proportion up to about 

 iVhs of an ampere, after which the deflection is very nearly pro- 

 portional to the current. Similarly the results show that as the 

 strength of the magnet of the telephone increases, the amplitude 

 of the vibration likewise increases up to a certain limit and 

 then falls off. The maximum motion of the diaphragm for a 

 given value of the alternating line current employed is attained 

 before the core reaches half saturation. It also appears iha', in 

 general, the amplitude of vibration of the diaphragm increases 

 less rapidly than the current actuating the telephone. 



Agriculture is rapidly becoming more scientific. In 

 France the Sociele Nationale d' Agriculture lately charged a 

 special commission to study the question of agronomic maps, 

 designed to afford the farmer useful indications on the phy-ical 

 and chemicti qualities of land, so that he may know how to 

 improve it, what manures to apply, and in what quantity, &c. 

 In an interesting report on behalf of this commission (sum. 

 marised in Rev. Gen. de Sciences) M. Carnot represents that the 

 time is now ripe for production of cantonal and communal 

 agronomic map?, on a Urge scale ; and a number of suggestions 

 are offered as to how the work should be done. 



There is now a general tendency in Russia to introduce some 

 teaching in agriculture and horticulture into the primary schools. 

 Both private persons and the Provincial authorities freely give 

 grants of land to the schools and to the teachers' seminaries for 

 their fields and orchards, and in many schools the plots of arable 

 land and gardens attended to by the pupils become small centres 

 of agricultural and horticultural education. In Caucasia the 

 same tendency is even more pronounced, and no belter idea can 

 be given of the extent of this new movement than by giving the 

 following facts relative to the primary schools of Kuban, a pro- 

 vince of Northern Caucasia. This year ten schoolmaster^ have 

 been invited to attend the lectures upon sericulture and bee-keep- 

 ing at the schools of the Cossack villages, Armavir and 

 Labinskaya. The inspector of the schools has acquired, with 



NO. 1233. VOL. 48] 



the modest grant of ;^35, thirty appliances for raising silk- 

 worms, and five arrangements for each school for pumping out 

 honey from the beehives, and preparing the artificial wax 

 honeycombs ; in addition to which, ten schools have been sup- 

 plied with apparatus for silkworm culture, while others have 

 been supplied with seeds of plants of special use to bees. All 

 schools which have gardens of silkworm trees have been sup- 

 plied with seeds of the tree, and 20,000 young trees have 

 been distributed among them. Fourteen schools are ex- 

 pected this year to carry on the silkworm culture, and ten other 

 .'-choolsare already carrying on experiments relative to the same. 



In the current number of the Entomologists' Monthly Maga- 

 zine, Mr. R. McLachlan, F.R.S., in an article on the extinction 

 of several species of British butterflies within recent years, and 

 the decadence that appears to be going on with respect to 

 others, suggests the enforcement of a close-time to last continu- 

 ously during the whole of a series of five or ten years. 



In a recent paper to a Christiania journal on the melting of 

 inland ice (whereby glaciers are prevented from growing in- 

 definitely in thickness, notwithstanding additions above the 

 snow line), Herr Schiotz attempts to estimate the three factors 

 concerned in the interior fusion, viz. earth heat, friction, and 

 pressure, and arrives at the result that a more important agent 

 than any of these (in hindering glacier growth) is solar heat 

 melting the surface ice below the snow line (Naturw. Rdsch. , 

 No. 21). 



A PARAGRAPH de.scribing a supposed earthquake felt in the 

 Isle of Man on the afternoon of May 5 was published in several 

 London and provincial papers. Mr. Charles Davison writes us 

 to the effect that his inquiries show that the shocks were due, 

 not to earthquakes, but to the firing of heavy guns from a 

 battleship situated near the island. 



During the cutting of a tunnel at the Notabile Terminus of the 

 Malta Railway (writes Mr. N. Tagliaferro in the Mediterranean 

 Naturalist) a piece of lignite, of dimensions about H by i by 

 I inches, was found embedded in the blue variety of the upper 

 globigerina limestone. The upper layers of this limestone 

 appear to be contemporaneous with the Langhian series of the 

 miocene beds of Italy, and were probably deposited on an ascend- 

 ing sea-floor at a depth of nearly 300 fathoms. The discovei^ of 

 lignite in these beds is, therefore, of some importance. 



Writing in Science of May 5, Dr. Morris Gibbs says that the 

 results of observations of the songs of fifty different species of 

 birds shows that the notes do not change in quality as a result 

 of change in emotion. After robbing nests he has waited and 

 listened, allowing ample time for the male to learn of the spolia- 

 tion. In each instance the male, upon returning to the empty 

 nest, at once burst into song, and though it is possible that the 

 song expressed much sorrow or complaint. Dr. Gibbs could 

 never distinguish any difference between it and the warbling he 

 was accustomed to hear. 



In the Lancet of June 10, Dr. Edwin Haward calls attention 

 to a point with respect to proofs of death, which, in conse- 

 quence of the growth of opinion in favour of cremation, is of 

 great importance. Sir B. W. Richardson and himself had to 

 decide in a particular case whether life was or was not extinct. 

 Of ten tests applied to the body, eight indicated that death was 

 complete. These were (i) heart sounds and motion entirely 

 absent, together with all pulse movement ; (2) respiratory 

 sounds and movements entirely absent ; (3) temperature of the 

 body the same as that of the surrounding air in the room ; (4) 

 a bright needle plunged into the body of the biceps muscle and 

 left there showed no sign of oxidation on withdrawal ; (5) inter- 

 mittent shocks of electricity passed through various muscles and 

 groups of muscles gave no indication whatever of irritability ; 



