December 2, 1915] 



NATURE 



379 



boiler fall to a dangerous extent, the plug becomes 

 hot, melts, and blows out, thus extinguishing the fire 

 before overheating of the furnace plates can take place. 

 It is well known that the behaviour of fusible plugs 

 ii somewhat erratic, and that they may be a source of 

 danger on account of the false sense of security which 

 they induce. It appears that there are two types of 

 failures, those in which an oxide is formed as an inter- 

 locking network throughout the tin of the filling, and 

 those in which the oxide forms as a solid hard mass 

 at the fire end of the plug. In more than looo plugs 

 examined, lead and zinc were found to be the principal 

 impurities present, and an explanation of the forma- 

 tion of the network type of oxidation is found in the 

 presence of zinc in amounts varying from 0-3 to 4 per 

 cent. The use of pure tin of the quality of Banka 

 (lead, traces up to 001 per cent. ; zinc, traces) or of 

 Straits (lead, up to 008 per cent. ; zinc, traces up to 

 0015 per cent.) would probably eliminate the danger 

 of oxidation of these plugs in service. 



A PAPER on the chemical and mechanical relations 

 of iron, molybdenum, and carbon was read at the 

 Institution of Mechanical Engineers on November 19 

 by Profs. J. O. Arnold and A. A. Read. Practical 

 metallurgists estimate from lathe and drill experi- 

 ences that, roughly, the steel-hardening power of 

 molybdenum is from two to three times as great as 

 that of tungsten. Theoretically, one atom of carbon 

 is about 228 times as powerful in producing hardenite 

 in true ferro-molybdenum steel as it is in forming 

 the hardenite of true tungsten steel. Unfortunately, 

 molybdenum is much more erratic in its behaviour 

 than tungsten, and the latter, though the less power- 

 ful element, still sits unshaken on its throne, because 

 of its trustworthy behaviour. The authors direct 

 attention to the exceedingly poor mechanical proper- 

 ties of molybdenum steels compared with the corre- 

 sponding steels containing tungsten. High moly- 

 bdenum steel quenched out at a proper hardening 

 temperature is very brittle, and it is clear that so 

 powerful a steel-producing element should be used 

 sparingly, avoiding large percentages. With low 

 percentages it exerts a beneficial influence on certain 

 classes of steel, when used cautiously either per se, 

 or to replace about 25 times its percentage of tungsten. 



The annual report of the Board of Regents of the 

 Smithsonian Institution for the year ending June 30, 

 1 9 14, has been received from Washington. The first 

 part of the volume, which runs to 729 pages, is 

 devoted to the report of the secretary, which contains 

 a summary of the researches and explorations 

 carried out under the auspices of the institution, and 

 eight appendices dealing with the year's work of the 

 United States National Museum, the Bureau of 

 American Ethnology, the National Zoological Park, 

 the Astrophysical Observatory, and other organisations 

 subsidised by the institution. But the most attractive 

 section of the volume is the general appendix of nearly 

 600 pages containing thirty-two articles on recent 

 advances and developments in science. These contri- 

 butions are selected from scientific publications all over 

 the world, and many are not easily accessible. The 

 following translations of foreign scientific papers de- 

 NO. 2405, VOL. 96] 



serve special mention : — Modern theories of the sun, 

 M. Jean Bosler, astronomer at the Meudon Observa- 

 tory; Some remarks on logarithms apropos to their 

 tercentenary. Prof. L'Ocagne, professor at the Ecole 

 Polytechnique, Paris; The geology of the bottom of 

 the seas, Prof. L. de Launay, professor at the Ecole 

 supdrieure des Mines, Paris ; Recent oceanographic 

 researches. Dr. Ch. Gravier; Homceotic regeneration 

 of the antennae in a plasmid or walking-stick, Mr. 

 H. O. Schmit-Jensen, of Copenhagen; Latent life : its 

 nature and its relations to certain theories of contem- 

 porary biology, Dr. Paul Becquerel ; Excavations at 

 Abydos, M. Edouard Naville; The r61e of depopula- 

 tion, deforestation, and malaria in the decadence of 

 certain nations, Dr. Felix Regnault ; and a sketch of 

 the life of Eduard Suess, by M. Pierre Termier, of 

 the Paris Academy of Sciences. As usual, the volume 

 is profusely and beautifully illustrated. 



OUR ASTRONOMICAL COLUMN. 



Comet 19 15^ (Mellish). — The Copenhagen telegram 

 announcing the discovery of this comet gave its posi- 

 tion on September 19. According to the Astrotwmische 

 Nachrichten (No. 4820), it was first seen by Mr. 

 Mellish on the night of September 13, whilst on Sep- 

 tember 18 it was independently found by van Bies- 

 broeck, Yerkes Observatory. 



OccuLTATiONS BY THE MooN. — On the evening of 

 December 10 the distant planet Uranus will be occulted 

 by the moon. The disappearance of Uranus will 

 occur at 6.2 p.m., and the reappearance at 6.10 p.m., 

 so that the object will be hidden for a short period 

 only by the limb of the moon in the apparent S.E. 

 region of her disc. She will be four days old at 

 the time, and visible as a narrow crescent with the 

 opaque part perceptibly involved in earthshine. At the 

 time of occurrence of the phenomenon the objects will 

 be situated in the S.W. sky at a low altitude. Our 

 satellite sets at 8.28 p.m. 



On the night of December 18 some of the stars 

 forming the Pleiades group will suffer occultation 

 between iih. 55m. and i3h. 51m. astronomical time. 

 The occultation of these stars, and also that of Uranus 

 on December 10, will require a fairly good telescope 

 to be witnessed effectively, as the stars and planet 

 are small, and will be partially overcome by the 

 moon's light. This, however, refers more particularly 

 to the occultation of the Pleiades, which takes place 

 at a time when the moon is nearly full. 



The Perseid Meteors in 1915. — Meteoric astronomy 

 is not only considerably alive in this country, but is 

 also attracting increasing attention in the U.S.A., and 

 we learn that there has recently been a very great 

 increase in the membership of the American Meteor 

 Society, from a report by Mr. Charles P. Olivier on the 

 August meteor campaign (Monthly Reg. Soc. Pract. 

 Astr., vol. vii.. No. 6). Attention was mainly given 

 to secure data for estimating the heights of the Perseid 

 meteors. Observers situated at four stations ar- 

 ranged to maintain a watch on the same absolute 

 section of the earth's atmosphere from i2h. to I4h. 

 on each night from August 9-13 inclusive. Two 

 nights (10 and 11) were totally cloudy. In the present 

 report Mr. Olivier gives a summary of the observa- 

 tions made at one of the stations (Leander McCormick 

 Observatory). The maximum of the shower occurred 

 on August 12, whilst August 13 was notable for the 

 brilliancy of the meteors seen. The publication of the 

 complete results obtained will be awaited with con- 

 siderable interest. 



