August S, 1895] 



NA TURE 



547 



' if the sand had dislodged certain microbes present in the filter- 

 ing material. It would appear, therefore, of interest to obtain 

 in cases where the filtrate is unsatisfactor)' some particulars of 

 the microbes present in the effluent, and determine in what 

 relation they stand to the raw water microbes. 



The question of the audibility of fog-horn signals at sea seems 

 lestined to occupy a great deal of attention in naval circles. 

 Some time ago we gave a description of the American experi- 

 ments, which went to prove that round each siren there is a zone, 

 about I J nautical miles broad, within which f<jg-signals cannot 

 lie heard, although they are distinctly heard outside that zone. 

 These observations cannot now be treated w ith the incredulity 

 hey at first met with, since other experiments have confirmed 

 them. A series of such experiments are described in Hansa. 

 In one of these, the vessel steamed with the wind straight towards 

 the light-ship from a distance of 4A nautical miles. At a distance 

 if z\ miles the sound became faintly audible, and suddenly 

 uicre-ascd in loudness at 2.J miles, retaining the same intensity up 

 to two miles distance. From i^ to li miles the note was scarcely 

 .ludible, but then it immediately increased to such an extent that 

 it appeared to originate in the immediate neighbourhood of the 

 vessel. The steamer at this point reversed its c6urse, and the 

 fluctuation over this part of the course was found to be the same, 

 •xcept that it was even more strongly marked. Reversing again, 

 he vessel steamed over this distance a third time, and again the 

 Mjund disappeared at li miles and reappeared again, so loud 

 that it sounded as if the fc^horn was only two cables' lengths off. 

 Then, at half a mile, the sound disappeared entirely, to reappear 

 it quarter of a mile from the light-ship, after which it gradually 

 and steadily increased in intensity until the latter was reached. 

 It is time that this question, which is of great practical 

 importance, should be .systematically investigated. 



Til K second annual report of the Iowa (Geological Survey, 

 lealing with the work done during 1893, has just come to hand. 

 The Survey was organised just three years ago, and it has carried 

 out .some very valuable investigations during its comparatively 

 ^hort existence. The coal deposits of Iowa have received 

 special attention since the organisation of the Survey, and one 

 .olume descriptive of them was issued last year. But these 

 Icposits are far too extensive to be discussed in a single volume. 

 We have it on the authority of Dr. C. R. Keyes, the Assistant 

 State (Geologist, that the ar<;a of the coal measures in Iowa is 

 somewhat over twenty thousand square miles, and that isolated 

 carboniferous outliers, and the region bordering the productive 

 coal measures, which must he gone over in tracing the limits of 

 the formation, occupy fully five thousand square miles or more. 

 With reference to the beds of gypsum at Fort Itodge, Dr. Keyes 

 says the area covered by the gypsum contains, approximately, 

 twenty-seven square miles, and that, at the lowest estimate, 

 the mass of gypsum which is found available in the region is not 

 less than sixty millions of tons. Much valuable data with 

 reference to these deposits are given in the report, and also in- 

 firnialion in regard to the building .stones, clays, and other useful 

 mineral substances in Iowa. Though the Survey has primarily 

 a utilitarian point of view, it is clear from the report that the more 

 scieniific side of geology is not neglected. Prof W. II. Norton 

 contributes to the report a paper on the thickness of the 

 I'al.vdzoic strata in North-Western Iowa, based upon records of 

 a number of borings for artesian and other deep wells. Me also 

 gives the results of a study of Devonian and Carboniferous out- 

 liers in Kastern Iowa. The report is illustrated by thirty-four 

 figures in the text, and thirty-six plates ; the most striking of the 

 latter belong to a paper by Dr. Keyes, on glacial scorings in 

 Iowa. Two new localities showing cxce))lionally fine effects of 

 glacial action were found near the city of Burlington in 1893. 

 ' Ine of them is near Kingston, on the top of a bluff overlooki.ng 

 -NO. 1345, VOL. 52] 



the Mississippi river, and judging from the reproduction of a 



jAoiograph, it furnishes a very remarkable example of a glaciated 

 surface. I'rof Calvin, the Stale Cleologust, is t() be congratu- 

 lated upon the work carried on under his direction. The Survey 

 has lately lost Dr. Keyes, who has become State CSeologist of 

 Missouri, his place being filled by Mr. H. F. Bain. 



The fifty-sixth annual meeting of the Royal Botanic Society 

 will be held in the Cardens, Regent's Park, on Saturday after- 

 noon next, the loth inst., at one o'clock. 



-V D.\IXTY catalogue, in which many rare and valuable 

 geographical works are described, has been issued by .Mr. 

 Bernard Quaritch. The catalogue should be seen by all 

 interested in geographical literature. 



We learn from the Journal of Botany that the herbarium of 

 the British Museum has recently acijuired a very fine collection 

 of llepatica: made by Ilerr F. Stephani. It numbers about 

 10,000 specimens, and includes types of iioo new species 

 described by Herr Stephani. 



The Proceedings of the Liverpool Naturalists' Field Club for 

 1894 contain a record of a large amount of .scientific work done 

 in the way of botanical excursions in Lancashire, Cheshire, and 

 North Wales ; a list of carboniferous fossils found within twenty 

 miles of Liverpool ; and reports of papers read at the evening 

 meetings. The total number of animals and plants that has been 

 recorded as occurring in the district, both living and extinct, is 

 given as 5735. 



The August nunilier of the Quarterly Journal of the Geological 

 Society contains a paper, l)y Dr. J. W. Gregory, on the Paliuonto- 

 logy and Physical (Seology of the West Indies. Among the 

 other papers we notice the following : — Prof. I. B. Harrison 

 and Mr. A. J. Jukes-Brown, on the chemical compo.ition of 

 oceanic deposits ; Mr. II. M. Bernard, on the systematic posi- 

 tion of the Tnlobites ; Prof. W. J. Sollas, on the mode of flow of 

 a viscous fluid ; Dr. C. S. Du Riche Preller, on fluvio-glacial 

 and inter-glacial deposits in Switzerland ; and Mr. E. T. Newton, 

 on fosisil human remains fnmi Palaeolithic gravels at Galley Hill, 

 Kent. 



The Royal College of Bclen, Havana, has just published its 

 magnetical and meteorological observations for the year 1890. 

 This institution h;is regularly issued reports .since 1S62, and the 

 continuous instrumental curves, which accomjiany the tables^ 

 have furnished valuable information for the investigation of 

 West India hurricanes. Since 1872, one of the late Padre 

 Secchi's well-known and expensive meteorographs has been 

 regularly at work at Havana, and is said to give very satisfactory 

 results. -We note that an attempt is matic each month to connect 

 the magnetical w ith the atmospherical disturbances. 



We have received from the Jesuit College of Qua, pro\ ince of 

 Burgos, a pamphlet containing meteorological oliservalions made 

 twice daily, with monthly and yearly results for the years 18S3- 

 1894. The Observatory is 1900 feet above sea-level, and is 

 rather sheltered ; but the summary of the climate of that part of 

 Spain by Prof. X'alladares, and the observations of cirrus clouds 

 and iheir connection with atmfispheric disturbances, are valuable 

 contributions to meteorological science. During the twelve 

 years in question, the extreme shade temperatures varied from 

 l''"3 to 100°, the annual mean being 5I°'8, and the aver.age 

 yearly rainfall was 22 inches. 



M. C.AsiMiR IJE C.wnoi.i.K contrilmtes to the Archives des 

 Sciences Physiques el Naturelles an important iiajjer on the 

 latent life of seeds. From a series of experiments, chiefly on 

 seeds of wheat, oat, and fennel, he concludes that dormant 

 seeds pass through a period of completely suspended animation, 



