586 



NA TORE 



[April 20, 1893 



Clark, of the Johns Hopkins University, on the surface 

 configuration of Maryland. The state is divided into three 

 districts: the Appalachian Region, the Piedmont Plateau, and 

 the Coastal Plain The inland border of the Coastal Plain 

 marks the head of navigation, above which the inclinations of 

 the valleys rise more steeply. This boundary is called the 

 "Fall-line"; along it the larger cities of the Atlantic sea- 

 board have grown up, and it marks out the leading highways of 

 trade which connect the north and south. The prolongation 

 of these three regions through other states is pointed out, and 

 atlention is directed to their importance as affecting tempera- 

 ture, rainfall, and the direction of the winds. 



The Berlin Academy has recently made the following grants : — 

 ;^5o to Dr. Wulf, of Schwerin, for prosecuiion of his crystal- 

 lographic researches ; £y:i to Prof. Taschenberg, of Halle, for 

 publication of his Bibliolheca zoologica ; £^o to Dr. Herz, of 

 Vienna, for carrying further the reduction of the observations at 

 the Kuffner Astronomical Observatory ; £iTS to Prof; Selenka, 

 of Eriangen, for a journey to Borneo ar^d Malacca to investigate 

 the development of apes, and especially the orang ; and £2^ to 

 Prof. Keibel, of Freiburg, forhis researches on the development- 

 history of the pig. 



The relations of the universities to the county councils in 

 respect to technical education will be discussed to- day and to- 

 morrow at a conference which will meet at Cambridge in accord- 

 ance with arrangements made by the Cambridge University 

 Extension Syndicate. The conference will be attended by 

 representatives of- county councils and universities, and by 

 other persons interested in the subject. Cambridge har, during 

 the last year provided courses of lectures on various scientific 

 subjects coming within the scope of the Technical Instruction 

 Acts for eleven Courty Councils as well as for the technical 

 education committees of other local authorities. A large part of 

 the work done has consisted of simple scientific teaching in 

 villages and small towns, and the attempt thus to bring the 

 universities into closer relation with rural districts has naturally 

 led to results of considerable interest and novelty. The results 

 of such work and the most effective way of making progress in 

 the future will be among the subjects discussed at the conference. 

 Another item will be the scheme for systematic instruction in 

 agricultural science at the university, devised by Prof. Liveing 

 and others in cooperation with several of the county councils. 



The Cambridge Universiy Extension authorities have already 

 announced as part of the programme of their summer meeting 

 to be held in Cambridge next autumn five courses of practical 

 work in science in the university laboratories and museums, the 

 subjects selected being chemistry, electricity, botany, physiology, 

 and geology. As, however, the date of the summer meeting, 

 July 29 to August 26, istooearly for many teachers in elementary 

 schools whose holidays fall during harvest time, arrangements 

 have also been made for two courses in agricultural chemistry, 

 specially adapted to meet the requirements of teachers sent with 

 scholarships by their respective county councils. Each course will 

 extend from August 25 to September 12 inclusive, and will thus 

 include sixteen working days, on each of which several hours' 

 work in the university laboratory will be provided. One course — 

 conducted by Mr. Fenton, one of the university demonstrators — is 

 intended for students who have done little or no laboratory work, 

 but have acquired a knowledge of theoretical chemistry, and 

 will be similar to the course given last year and attended by 

 about 120 county council scholars. The other course — conducted 

 by Mr. R. H. Adie, one of the Cambridge Extension lecturers 

 — will be more advanced in character, and will be adapted to 

 students who went through last year's course with credit, or have 

 done similar work elsewhere. Accommodation for 120 students 

 can be provided at these two courses. 

 NO. 1225. VOL. 47] 



Last month a stone, which is valued at 17,000 rupees, was 

 discovered at the Burma ruby mines. According io ih^ PioMter 

 Mail, this is the most valuable ruby which has come to light 

 for some considerable time past. 



M. Edouard Branly gives a further account of his -experi- 

 ments on the loss of the electrical charge of bodies in diffuse 

 light and in darkness, in this week's Comptes Rendus. He finds 

 that a disc of polished aluminium, if it is experimented on a few 

 days after being polished, behaves like most other metals ; i.e. 

 it slowly loses its charge, and the loss is approximately equal for 

 the two kinds of electricity and independent of the kind of light 

 to which it is exposed. If the disc has been freshly polished, 

 however, even in diffuse light the loss is rapid, and is only 

 slightly diminished by surrounding it by orange glass, thus 

 showing the loss not to be due, to any great extent, to the rays 

 at the more refrangible end of the spectrum. 



In the current number of the American [oiirnal of Sci^nce 

 there is a paper by Mr. I. Pupin, describing a method of obtain- 

 ing alternating currents of constant and easily-determined 

 frequency. For this purpose he uses a small transformer, whose 

 primary circuit contains an interrupter of peculiar design. This 

 consists of a stiff brass wire, stretched lietween the pole pieces 

 of two permanent horse-shoe magnets, and carrying at its middle 

 point a short amalgamated copper wire. At every vibration this 

 copper wire dips into a mercury cup and closes the circuit of a 

 battery ; the repulsion between the curreot in the wire and the 

 magnets serving to keep up the vibrations. The tension, which 

 can be adjusted without stopping the vibrations, is altered until 

 the wire is in unison with a tuning-fork of known pitch. In 

 order to diminish the intensity of the harmonics which are pre- 

 sent when the current is interrupted in this way, the primary of 

 the transformer is joined in scries with another coil, having a 

 movable iron core, and in parallel with a condenser of varialile 

 capacity. The capacity and self-induction of the circuit are by 

 these means altered till the natural period of the circuit corre- 

 sponds with the fundamental of the wire. The attainment of this 

 condition is shown by the sparking at the break being a mini- 

 mum. Under these circumstances the circuit acts as a resonator, 

 and selects from the complex E. M.F. that harmonic with which 

 it is in resonance, and strengthen-* it. 



For some considerable time continuous records have been 

 kept at Greenwich Observatory of the earth currents along ;wo 

 lines approximately at right angles. However, since the South 

 London Electric Railway has been working, the records, except 

 during a few hours of the night when the trains do not run, have 

 been so disturbed as to be quite valueless. These disturbances 

 show to what an extent the current, when there is no insula'.ed 

 return, strays, as the railway is nowhere within four miles of the 

 Observatory. In order to continue the earth current records 

 and if possible trace their connection with the disturbances of 

 the earth's magnetism. Prof. Mascart has had two earth-current 

 lines fitted with continuous recording galvanometers, placed in 

 the Pare Saint-Maur Observatory, and has so selected his lines 

 that one runs exactly north and south, and the other east and 

 west. In addition to the above a continuous record is kept 

 of the cui rents passing in .an aerial circuit, which is at all par:s 

 insulated from the earth. 



In the course of some investigations necessitating the elimina- 

 tion of small variations of atmospheric pressure, Dr. Carlo dei 

 Lungo constructed what appears to be a highly sensitive 

 mercury barometer. As described in the Riziita Scientifito- 

 Induitriale, it consists of a vertical tube of 20 mm. bore 

 and about a metre long, bent round at the bottom in the 

 ordinary way, but having the open end closed by a steel cap 

 screwed on to an iron collar attached to the tube. A long 



