November 12, 1891] 



NATURE 



39 



A MAMMALIAN tooth has just been discovered by Mr. 

 Charles Dawson, of Uckfield, in a Wealden bone-bed near 

 Hastings. The fossil much resembles one of the lower molars 

 of Plagiaulax, a genus well known from the Purbeck Beds of 

 Swanage. It is the first evidence of a mammal from the 

 Wealden formation, and will be exhibited and described by 

 Mr. Smith Woodward at the next meeting of the Zoological 

 Society, on the 17th inst. 



De Candolle states, in his " Origin of Cultivated Plants," 

 that maize is unknown in the wild condition. Some light may 

 possibly be thrown on the origin of cultivated maize, by the 

 discovery of a wild species, the only one of the genus, in 

 Mexico. It is described by Prof. Sereno Watson, in the 

 "Contributions to American Botany," under the name Zea 



We learn from the Journal of Botany that the great Index 

 of Genera and Species of Flowering Plants, on which Mr. B. 

 Daydon Jackson has been continuously engaged for nearly ten 

 years, is now ready for the printers' hands, and will be issued 

 by the Clarendon Press, under the title " Index Kewensis 

 nominum omnium plantarum phanerogamarum, 1 735-1885." 

 The work has been carefully revised by Sir Joseph Hooker, 

 who, besides annotating the manuscript, has undertaken the 

 care of the geographical distribution. 



If the weather during the approaching winter be as severe as 

 that which we had last winter, many persons jwill be likely to 

 take some interest in an invention which is attracting notice in 

 America. This is an electric snow-sweeper — a snow-sweeper 

 driven by an electric motor. The Engineering Magazine, of 

 New York, says that while the machine is driven along the track 

 of an electric railway by a motor ot 30 horse-power, taking its 

 current through the trolly wire, the two sweeping brushes are 

 each driven by an independent motor, and all the three motors 

 are reversible. It is stated that this plough is competent to re- 

 move from a track snow having a depth of from 3 to 12 inches, 

 while running at a speed of from 4 to 10 miles an hour. The 

 independent action [of the brush-motors enables them, when 

 necessary, to be run at a high rate of speed while the plough is 

 moved slowly along the track, and thus to cut away hard, com- 

 pacted snow, or drifts. It is said that the machine was thoroughly 

 tested last winter, and its effectiveness thereby completely de- 

 monstrated. 



It is known that ozone can be abundantly produced by the 

 electric silent discharge, and many years ago Siemens devised 

 an "ozone-tube" for the purpose, consisting of two thin glass 

 tubes, one within the other; the inner lined, and the outer 

 coated, with metal, to which alternating currents of high tension 

 are brought, acting on the gas to be ozonized within. From 

 recent experiments in Siemens and Halske's laboratory, it 

 appears that a good result may be had with only one dielectric, 

 and for this not only glass, but mica, celluloid, porcelain, or the 

 like, may be used. Thus the ozone-tube may be arranged with 

 a metallic tube within, and the outer tube a metal-coated 

 dielectric ; or the inner metal tube may have a dielectric coat, 

 while a metal tube is the inclosing body. As metals that are 

 little or not at all attacked by ozone, platinum, tin, tinned 

 metals, and aluminium are recommended. Through the inner 

 tube flows cold water, and through the space between the tubes 

 air, dried and freed from carbonic acid. Several such tubes 

 may be combined in a system, and worked with alternate 

 currents (for single tubes the continuous current with commur 

 tator is best). An apparatus of this kind is now at work in the 

 laboratory, yielding 2-4 mg. of ozone per second. Experiments 

 are being made in supplying compressed ozone for technical use ; 

 and this has been accomplished with a pressure of nine atnio- 

 NO. I I 50, VOL. 45] 



spheres. One use of ozone, on which Herr Fiolich lays special 

 stress (in the recent lecture from which these data are taken), 

 is the disinfection and sterilization of water. And doubtless 

 with an abundant supply of the substance, the use of it would be 

 greatly extended. 



Mr. a. Crawford, the manager of the travelling dairy 

 connected with the Department of Agriculture, Victoria, is 

 able to give a very favourable report of the results of the 

 operations of the dairy during the last two years. It has been 

 the means, he says, of very largely improving the general 

 average of both cheese and butter sent to market. A good 

 many pupils have been taught who had never made butter o"" 

 cheese before, and several of them are now managing factories. 

 In nearly all the places he has visited Mr. Crawford has lectured 

 on dairy farming ; and in many cases he has gone to outlying 

 districts as well as to important centres. 



At the recent general meeting of the German Anthropological 

 Society, Prof. Montelius, of Stockholm, delivered two remark- 

 ably interesting archaeological lectures. In the first he dealt 

 with the chronology of the Neolithic Age, especially in 

 Scandinavia. The monuments of that age, he said, belonged 

 to three different periods. First, were free-standing dolmens 

 without passages ; next, passage-graves ; finally, stone cists. 

 The last are later in proportion to the completeness with which 

 they are covered by the mounds heaped over them. Behind 

 the periods represented by these classes of monuments was a 

 Neolithic period from which no grave of any kind is known to 

 have survived. It has left traces, however, in its implements, 

 which are of an earlier form than the various sorts found in the 

 different groups of monuments. The Scandinavian forms of 

 Neolithic weapons, implements, and ornaments are closely akin 

 to those which have come down to us in the rest of Europe, 

 especially in North Germany, England, Italy, and even Cyprus. 

 This may be held to prove that there was a more or less active 

 commercial intercourse between Scandinavia and the Continent 

 at a very remote time. To this commercial intercourse Prof. 

 Montelius is disposed to attribute the relatively high civilization 

 of Scandinavia in the Neolithic Age. Prof. Montelius also 

 contends that the various periods of the Neolithic Age in 

 Scandinavia were more nearly contemporaneous with those of 

 other parts of Europe than has hitherto been generally supposed- 



In his second lecture Prof. Montelius treated of the Bronze 

 Age in the East and in Southern Europe. He distinguished the 

 following periods : — (i) A copper period without bronze, re- 

 presented by the finds of Richter in Cyprus and those obtained 

 by Schliemann from the first city at Hissarlik. (2) The bronze 

 period in the islands of the ^gean Sea, Rhodes, Crete, &c. 

 (3) A later bronze period — («) with shaft tombs at Mycenae, 

 {b) with bee-hive tombs in the neighbourhood of Mycenae, 

 Orchomenos, &c. These cities had not a pure Hellenic civiliza- 

 tion, but must be regarded rather as Oriental colonies. The 

 knowledge of bronze certainly came to Europe from the East ; 

 not by way of Siberia and Russia, nor across the Caucasus, but 

 probably through Asia Minor and the Mediterranean to Italy 

 and Spain, whence it rapidly spread to Gaul, Britain, and other 

 countries. 



A peninsula called Keweenaw Point, jutting into Lake 

 Superior from the southern shore towards the north-east, is 

 famous as the centre of a vast copper-mining industry. Last 

 year the mines produced no less than 105,586,000 pounds of re 

 fined copper, and it is estimated that during next year production 

 will be increased by at least 20 per cent. Mr. E. B. Hinsdale, 

 who contributes to the latest Bulletin of the American Geo- 

 graphical Society an article on the subject, has much that is 

 interesting to say about the numerous prehistoric mines which 

 have been found in this region. These ancient mines — judging 



