October 27, 1892] 



NATURE 



617 



the results. The title is well chosen, for the work treats of 

 the relations which connect the different phenomena ; it also 

 gives all necessary precautions for ensuring the accuracy of the 

 observations. Particular attention is paid to the important sub- 

 ject of diurnal and annual variations of the different elements, 

 and to the various points to be noted, while the different theories 

 of atmospherical electricity are explained at considerable length. 



A BEAUTIFUL and instructive lecture experiment, illustrative 

 of the conditions of the heated atmosphere which give rise to the 

 mirage, is described by MM. J. Mace de Lepinay and A. Perot, 

 in their "Etude du Mirage," which appears in the Annales de 

 Chimie et de Physique. Water is poured into a long rectangular 

 trough with glass slides, and covered with a layer of alcohol 

 about 2 cm. thick, containing a trace of fluorescene. After a few 

 hours, during which the alcohol diffuses slowly through the 

 water, a flat beam of light is sent through the mixture at a very 

 slight inclination to the horizon. Under these conditions a 

 kind of garland of light is seen to traverse the liquid, due to a 

 series of curvilinear deflections or " mirages " in the less highly 

 refractive water below and total reflections at the upper surface 

 of the alcohol. 



Prof. W. Crookes and Prof W. Odling, in their report on 

 the London Water Supply for the month of September, are able 

 to give an excellent account of the 182 samples which they 

 analyzed. All were found to be perfectly clear, bright, and 

 well filtered. In respect to the smallness of the proportion of 

 organic matter present, the character of the water furnished by 

 the seven companies continued to be entirely satisfactory, the 

 mean amount of organic carbon in the Thames-derived supply, 

 for example, being 'iiS part, and the maximum amount in any 

 single sample examined being but *I45 part, in 100,000 parts of the 

 water — numbers practically identical with those of the previous 

 month, or *l 15 part for the mean, and I '52 part for the maxi. 

 mum, amount. The average of the past six months, in the case 

 of the Thames-derived supply, has amounted only to ' 1 16 part of 

 organic carbon in 100,000 parts of the water, with a maximum, 

 twice met with, of '152 part in any individual sample. The 

 authors of the report do not expect that with the coming on of 

 autumn and winter this low average will be much longer sus- 

 tained. They note that the water supply to London is habitually 

 at its best during the hot season, when a high quality of the 

 supply is more especially called for. 



An interesting report on the Congress of the Library Asso- 

 ciation of Great Britain, held at Paris last month, was read on 

 Tuesday before the Salford Royal Museum and Free Libraries' 

 Committee. It was prepared by Mr. Alderman W. H. Bailey, 

 who had naturally a good deal to say about the Paris Free 

 Libraries. The governing bodies of almost all these institutions 

 consider that there are many reasons why the libraries should 

 be closed in the daytime when respectable artizans are engaged 

 in earning their living. Books are therefore given out for 

 two hours every evening of week days, generally from eight to 

 ten o'clock, and also for two hours every Sunday morning. Mr. 

 Bailey and the other members of the Congress were delighted 

 with the Paris Libraries of Industrial Art, to which they de- 

 voted much attention. These Libraries — which, like the Free 

 Libraries, are under municipal control — are in the artizan dis- 

 tricts of Paris. Books, patterns, prints, drawings, and photo- 

 graphs are lent out. " Not only do house decorators," says 

 Mr. Bailey, "find designs and books relating to work, but fan 

 painters, porcelain modellers, designers of iron and bronze gates, 

 medieval metal workers, cabinet makers, builders, and all workers 

 in the constructive as well as the decorative arts may here find 

 stimulus and draw inspiration from the wealth of examples on 

 the shelves and walls." Free lectures are delivered in the winter 

 on industrial art and science, and on the designs, books, and 

 models in the Libraries. 



Various experiments which are being made in France with 

 a view to the improvement of the potato have attracted a good 

 deal of attention in Australia. According to a statement recorded 

 in the Agricultural Gazette of New South IVales, no fewer than 

 no growers have obtained from a variety known as " Richter's 

 Imperator," from twelve to twenty tons per acre, while the 

 average is over fourteen tons to the acre. The Minister of 

 Agriculture in New South Wales has approved of one hundred- 

 weight each of this and any other three sorts highly reputed in 

 France being imported for experimental purposes. 



At a recent meeting of a society of French agriculturists, it 

 was stated by Baron Bertrand-Geslin, that ten or twelve years 

 ago a disease appeared among the chestnut trees in central and 

 north-western France, and destroyed them in great numbers. 

 The wood, moreover, could not be utilized for heating purposes. 

 At this juncture an enterprising person appeared, who bought 

 up large quantities of this dead wood and sent it by canal to 

 Nantes, where he had works established for utilizing it in the 

 tanning of leather. Chestnut wood contains, in fact, 5 to 6 

 per cent, of tannic principles, whereas oak contains only 3 or 4. 

 By the means adopted in these works the principles are con- 

 centrated in a sirupy liquid of great strength. This establish- 

 ment has become very important ; it absorbs annually thirty to 

 thirty-five million kilogrammes of wood of these dead chestnuts 

 from three departments traversed by the canal from Nantes to 

 Brest, and expends about 120,000 francs per annum, a consider- 

 able reduction of the loss sustained by the landowners. It was 

 mentioned, however, by M. Paul Becquerel, in reply to a 

 question as to competition of the new extracts with bark, 

 that those extracts, which are products allied to tan, do not give 

 the same results, or leather of such good quality, and many 

 tanners who have used them have returned to the old methods of 

 tanning. 



Dr. R. Munro contributed to the Times of Monday a long 

 and most interesting account of the recent discovery of an 

 ancient lake-village in Somersetshire. The site is about a mile 

 north of Glastonbury. Before excavatiois were begun, there 

 were sixty or seventy low mounds, rising from one to two feet 

 above the surrounding soil and measuring from twenty to thirty 

 feet across. That the mounds were of archaeological interest 

 was first suspected by Mr. Arthur Bulleid, who began to ex- 

 cavate some of them during the present summer, and was soon 

 rewarded by making striking discoveries. Woodwork corre- 

 sponding to that of the crannogs of Scotland and Ireland has 

 been exposed, and among the objects which have been recovered 

 are some of bronze, a few of iron, and various specimens of 

 pottery. Mr. Bulleid has also dug out " a splendid canoe 

 neatly formed out of the trunk of a tree." This was found about 

 a quarter of a mile from the settlement. It would seem that 

 the inhabitants, after a period of long occupancy, indicated by 

 a succession of superimposed hearths, were flooded out of their 

 homes, for an accumulation of flood soil now covers the whole 

 meadow to the extent of 12 inches to 18 inches in depth. The 

 surrounding district is richly cultivated, but, in looking over an 

 old map of the date of 1668, Dr. Munro found that it contained 

 a lake called the " Meare Poole," into which three streams 

 debouched, and from which the site of the present discovery 

 could not be far distant. He suggests that this lake had 

 larger dimensions in earlier times, and that when the settle- 

 ment was founded the locality was a shallow lake or 

 marsh. The old map represents the district lying imme- 

 diately on the north-west borders of the "Meare Poole" 

 as inhabited by the Belgae. Dr. Munro is strongly inclined to 

 think that the settlement belongs to the so-called Late Celtic 

 period. This he would simply call the Celtic period, for there 

 is no evidence, he believes, of earlier Cellic remains in Britain 



NO. 1200, VOL. 46] 



