82 



NATURE 



[May 25, 189: 



near the horizon, as seen from a high mountain peak." That 

 Jupiter is not self-luminous, and that outside its cloud surface 

 is situated a rare atmosphere capable of producing a measurable 

 refraction, are two of the results of these observations, and taking 

 the refraction at the cloud surface, the value o"'5o x o"'05 pro- 

 bably is not far from the truth. 



The Moon's Surface. — Under the title of "The Moon's 

 Face," a study of the origin of its features, we have before us a 

 small book of fifty pages, containing the address, as retiring 

 President, of Mr. G. K. Gilbert, before the Philosophical 

 Society of Washington (Bulletin, vol. xii., pp. 241-292). After 

 giving a short survey of the various theories that have from 

 time to time been suggested as explaining the origin of the 

 features on our satellite's surface, Mr. Gilbert has been led to 

 put forward what he terms a "moonlet theory," which '"not 

 only harmonises with the varied details of crater character, but 

 aids in the explanation, and even in the history, of the other 

 features of the moon's surface." The hypothesis may be stated 

 .as follows :— Previous to the existence of the moon the earth 

 was circled by a ring analogous to that which surrounds Saturn. 

 The small bodies or satellites constituting this ring in time 

 Gradually coalesced, first into a large number of nuclei, and 

 finally into one, this nucleus being our moon. The lunar 

 craters are, to use Mr. Gilbert's own words, " the scars pro- 

 duced by the collision of those minor aggregations, or moonlets, 

 which last surrendered their individuality." In discussing this 

 hypothesis the inquiry is carried on three lines : an investiga- 

 tion of the ellipticity of the lunar craters, experimental inves- 

 tigation of the relation between the angle of incidence and 

 ellipticity of impact craters, and of the orbital relations affect- 

 ing the incidence angles of moonlets. With regard to some of 

 the peculiar features of the lunar surface, let us briefly refer to 

 some of the explanations given here. In the production of 

 small craters small moonlets were employed, the cups being 

 moulded as the result of collision. For large craters, greater 

 moonlets are supposed to have been in action, the rims round 

 the cups being raised partly by the overflow at the edges of the 

 cup, or resulting in the upheaval of the surrounding plain in all 

 directions. The central cone is accounted for by supposing 

 that the top parts of the walls of the cup are so "weakened by 

 the efforts of heating," that they consequently fall into the 

 centre of the cup from all sides. In the region of the Mare 

 Imbrium he supposes that a collision of great violence occurred, 

 dispersing in all directions a deluge of material " solid, pasty, 

 and liquid." The outrush from the Mare Imbrium thus 

 introduces the elements necessary to a broad classification of 

 the lunar surface. Smooth planes were produced by the 

 liquid matter, parts were ground or sculptured by the solid 

 matter, while some features were left entirely untouched. 

 Such are one or two of the origin of surface features as put 

 forward by Mr. Gilbert in his moonlet theory. That they 

 are ingenious and lack not interest is true, but that the 

 hypothesis itself is likely to be received with anything like 

 favour seems very doubtful, since our present knowledge of the 

 way nature works shows us that the last minor aggregations or 

 moonlets could not very probably act in the way indicated 

 above, because the state of the nucleus about that time would be 

 one of intense heat in consequence of the collisions, and there- 

 fore would not be capable of receiving lasting impressions as 

 required by the hypothesis. 



AMEDfiE GuiLLEMiN.— It is With great regret that we have 

 to record the death of M. Amedee Guillemin, which occurred 

 recently in France. Many of our readers will have read the 

 most interesting and valuable books which he wrote, setting 

 forth scientific facts in a popular light. Of his many writings 

 perhaps that which is most familiar to us are the volumes entitled 

 "'The Heavens "and "The Forces of Nature," as translated into 

 English, and it is only quite lately that we had occasion to 

 notice a small volume, evidently his last work, dealing with 

 astronomical subjects, and entitled " L'Autres Mondes." 



GEOGRAPHICAL NOTES. 



Lieutenant R. Peary, the explorer of North Greenland, 

 has been reluctantly compelled to relinquish his projected 

 lecturing tour in Europe, as all his time must be devoted to 

 preparations for his new expedition toward the North Pole, 

 which he hopes to commence this summer. 



NO. 1230, VOL. 48] 



The Governments of Sweden and Denmark have entrusted 

 Prof. Otto Pettersson with the planning and direction of a 

 series of simultaneous observations on the physical con- 

 dition of the Skagerrack, Kattegat, and Baltic Sea. These 

 observations are to be made on four days, three months apart, 

 and commenced on May I, 1893. Simultaneous observations 

 between the Moray Firth and the north of Shetland would 

 greatly enhance the value of the Scandinavian results, and it is 

 possible that the Fishery Board for Scotland may undertake this 

 work, at least on some of the observing days. 



Captain Richard Pike, well known as an Arctic navigator 

 in recent American expeditions, died at St. John's, Newfound- 

 land, in the beginning of May. In 1881 he conveyed the 

 Greeley expedition to Lady Franklin Bay, and would have 

 brought relief to the party, and saved the gallant explorers from 

 their terrible experiences of starvation in 1883, had he not on 

 that occasion been put under the orders of a United States 

 cavalry officer, whose mismanagement ruined the expedition. 

 Captain Pike's last Arctic work was the transport of Peary's 

 expedition to McCormack's Bay, and his return for them in the 

 sealer Kite. He had the reputation of being the best practical 

 navigator of the Newfoundland Sealing Fleet, and his experience 

 will be missed in connection with Lieutenant Peary's new ex- 

 pedition, which Captain Pike was to have taken north this 

 summer. 



The anniversary meeting of the Royal Geographical Society 

 will be held on Monday, the 29th, at 2.30 p.m. From the 

 circular calling the meeting we observe that a very considerable 

 change in the composition of the Council is contemplated. The 

 President, Sir M. E. Grant Duff, does not seek re-election, in 

 the hope, as he hinted at the anniversary dinner, that his " leap 

 into the gulf in the cause of women " will heal the recent dis- 

 sensions in the Society, p.nd enable the scientific work in which 

 it is engaged to be caiiied on without interruption. Mr. 

 Clements Markham, F.R.S., has accepted the nomination of 

 the Council as President. Captain Wharton, R.N., F.R.S., 

 is proposed as a new Vice-President, and the following, amongst 

 other names, are proposed as new members of Council : — -Ad- 

 miral Lindesay Brine, General T. E. Gordon, author of " The 

 Roof of the World;" Mr. G. S. Mackenzie, of the British 

 East Africa Company : Colonel C. M. Watson, and Mr. W. H. 

 Hudlestone, F.R.S., President of the Geological Society. These 

 nominations are subject to the approval of the annual meeting, 

 which is expected to be unusually large and representative. 



BACTERIA, THEIR NATURE AND 

 FUNCTION.^ 



A WELL-KNOWN English writer a short time ago informed 

 -^- the public that Prof, von Pettenkofer, the distinguished 

 veteran in sanitary science in Munich, expressed the opinion 

 that "the atmospheric envelope of this globe is at present in a 

 bacillophil humour." Expressions such as these have been 

 repeatedly used in one form or another, some more, some less 

 witty ; the intention being, of course, to convey an exaggerated 

 impression of the frame of mind of over-zealous enthusiasts. 

 By such expressions more or less distinguished speakers 

 and writers have been enabled to exhibit the smartness of 

 their phraseology. Thus one distinguished professor re- 

 lieved the anxiety of his students by the jocular observation 

 that idleness and laziness will probably be found to be 

 due to a specific bacillus, while another no less profound 

 writer enunciated that crime and inebriety are probably due to 

 bacilli. With regard to the distribution of bacteria, as well 

 as with regard to their action, we meet with statements 

 which are almost made humorous by smartness of exaggera- 

 tion. Under the cover of the title "Science Notes," one 

 of the London papers offered to its readers for breakfast 

 the following palatable dish: — "In a grain of butter you 

 have 47,250,000 microbes; when you eat a slice of bread 

 and butter, you therefore must swallow as many microbes as 

 there are people in Europe." Here it ought to be stated that a 

 grain of solid matter of London se7vage contains only a small 

 fraction of this number of microbes. But leaving these silly 

 exaggerations and those grotesque sayings to their authors for 



^ Lecture delivered at the London Institution, on February 27. 1803, by 

 E. Klein. ALD., F.R.S., Lecturer on General Anatomy and Physiology at 

 the Medical School of St. Bartholomew's Hospital, London 



