Feb. lo, 1881] 



NATURE 



347 



of Sciences by Arago. The Coiiiptes rmdus states that Arago 

 was asked to inquire into the properties of this] curious pheno- 

 menon, but it does not appear that he made any effort to comply 

 with the request of the Academy. 



After a series of experiments which have proved successful, 

 the Administration of French lighthouses has given an order to 

 M. de Meritens to build six magneto electric machines for the 

 three first lighthouses which are to be illuminated by electricity. 



The Chemical Section of the Russian Physico-Chemical 

 Society has, on the proposal and at the expense of Mr. V. J. 

 Kagosine, established a competition for a prize of 750 metallic 

 roubles (3000 francs) for the invention of a lamp intended to 

 burn the heavy oils of petroleum (naphtha), /.(•. the parts of the 

 raw petroleum which distil after the kerosene or ordinary 

 petroleum (density from 079 to o'83 at 20° C.) ; as also astral 

 oil (density o'83 to 0'85 at 20° C), but before the oils intended 

 for greasing purposes (density about o'SS), i.e. oils whose 

 density is from 0-85 to 0-88 at 20° C. The lamps ought (l) to 

 be as simple as possible in construction, so that they may be 

 easily manufactured and manipulated ; (2) only glasses existing 

 already in the retail trade to be used, if they are used at all ; (3) 

 to bum, without giving either soot or smell, the heavy oils whose 

 density is at least betweeno-865 and 0-875. The lamps must be 

 sent in by January 12, 18S2, and three specimens of each 

 should be sent, accompanied by a detailed description in Russian, 

 French, German, or English. There is no restriction as to 

 nationality. Further information may be obtained from the 

 Secretary of the Society, St. Petersburg. 



We would call the attention of our readers to a very valuable 

 and ingenious instrument which has been recently introduced by 

 Messrs. Francis and Co., the Telegraph Engineers, Hatton 

 Garden, London, for the purpose of receiving the " Greenwich 

 Time Signal" at the various telegraph stations and offices of 

 private firms who may be in communication with tlie Postal 

 Telegraph Service. Hitherto the passage of the time-signal 

 current at 10 a.m. along the wires gives no other indication of 

 its presence than a deflection of the needle of ordinary instru- 

 ments, and a corresponding movement of the armature of the 

 Morse Ink-Writer and Sounder, so that unless a sharp look-out 

 be kept with the eye constantly directed to the instrument, the 

 actual time of signal may be lost, perhaps also again to be lost 

 on the following day through similar accident. By the new in- 

 strument, however, the instant the current is sent the needle on 

 its dial is deflected, and simultaneously a bell rings and con- 

 tinues to ring so long as the current is passing. The index- 

 needle, or in other words the needle of the galvanometer, which 

 is the principal feature of the invention, when deflected, presses 

 against a small spiral spring surrounding the stops or ivory pins 

 on the dial plate, and by this contact the galvanometer forms 

 itself into a " relay " and brings a local battery in circuit with 

 the bell, which is contained in the same instrument, so that 

 when the first part of the time-signal is sent the needle is de- 

 flected, and at the same moment tlie bell rings ; thus attention 

 to the time is at once arrested. It should be mentioned that the 

 resistance to the line, although low, is intended to be inserted 

 only during the transmission of the time-signal, as by means of 

 what is generally termed a " switch " the instrument is put on 

 and off the circuit at will, and employed only during the time 

 set apart for the transmission of the "Greenwich Time Signal." 

 However feeble the current may be, the galvanometer is so 

 sensitive that a deflection of its needle is absolutely certain, 

 whilst the bell cannot fail to answer to the power of its local 

 battery. We are informed that not only is Messrs. Francis and 

 Co.'s new instrument capable of doing what we have already 

 stated, but it may be made available for communication from 

 different parts of the building, an advantage which is certain to 



be recognised and approved by many conducting large business 

 establishments, where the saving of time in conveying messages 

 and giving orders is a matter which is not unfrequently of great 

 importance. 



A. P. S. WRITES : — During the late severe frost we .had a 

 number of bottles broken in our laboratory by the freezing of 

 their contents, and it is curious to observe what salts tend to 

 prevent such an occurrence. Out of thirty sets of reagents the 

 following were destroyed : — 27 ammonium oscalate, 7 calcium, 

 sulphate, 8 potassium ferrocyanide, i lead acetate. It is 

 remarkable that not one bottle of lime-water was frozen. That 

 calcium sulphate, which only conlains 5^^th of solid, should 

 freeze, is not astonishing ; but the ammonium oscalate bore 

 away the palm with ease, although the amount dissolved 

 was considerable. A single bottle of saturated solution of 

 alum was broken, also one of mercuric chloride. A curious 

 thing happened to one bottle, which shows, I think, that ice 

 does not expand suddenly when it freezes. I unstoppered ,a 

 bottle of Am„0 that was still liquid, when the contents imme- 

 diately solidified in my hand, without bursting the bottle. 

 The next day I found the ice had protruded 35 inches from the 

 neck of the bottle, carrying the stopper at its extremity. 



Those who wish to see women have every fair play in the 

 struggle for existence may be interested to know that at 399, 

 Edgeware Road, Mme. Lina from Geneva is prepared to do 

 good w ork as a practical watchmaker and jeweller. 



A NUMBER of holes of the same description as those which 

 have been observed at Blackheath have been opened in several 

 parts of Paris. These enigmatical holes are several yards wide, 

 long, and deep. Men of science are trying to solve the mystery 

 of their formation. 



A VERY satisfactory report was given at the recent annual 

 meeting of the Birmingham Natural History Society, which now 

 has apartments in Mason's College. The number of members 

 is 3 82. 



Mr. J. B. Jordan has issued a Ihtle pamphlet giving an 

 account of his glycerine barometer, with plate and tables of 

 correction for temperature. Stanford is the publisher. 



Under the title of "All about Cardamoms, Botanical 

 Descriptions, Commercial Uses, and Modes of Cultivation," a 

 pamphlet of forty closely-printed pages has recently been issued 

 in Colombo from the office of the Ceylon Observer. In this 

 useful little pamphlet nothing new or original is professed to be 

 given, it is simply a compilation of all matter bearing on the 

 subject collected from all available sources, each article being 

 printed in its entirety and its source acknowledged. Thus we 

 find the article on Cardamoms from the latest edition of the 

 Encychpicdia Britaniiica, Fliickiger and Hanbury's Phannaeo- 

 gi-aphia, Beutley and Trimen's Medicinal Plants, and many 

 others. In this arrangement there is of course much repetition 

 of the same matter, but the idea is good as bringing together all 

 that has been published on a given subject whicli is frequently 

 scattered through many, and often inaccessible publications. 



The works for the Paris Exhibition of Electricity will soon 

 begin. A viaduct will be built for the English electrical 

 railway by Siemens, which will convey visitors from the 

 Place de la Concorde to the Palais de ITndustrie. The 

 internal arrangements will only be made at the end of 

 the Art Exhibition, which will take place from May to July. 

 The French exhibitors of the electric light have come to an agree- 

 ment in order to combine for the illumination of the nave 

 and other parts. They are trying to obtain from the High 

 Commission an indemnity for their working expenses. It is 

 desirable that the English Government appoint without delay 

 an agent on behalf of the intended English exhibitors, who 

 may be numerous, even in the light department. 



