n6 



SCIENTIFIC NEWS. 



[Aug. 3, i i 



in length and 20 feet wide. The iron pipes for convey- 

 ing the sludge to the ships will be carried under the 

 platform, and will be furnished at the end with a 

 delivery pipe, socketed to admit of a vertical move- 

 ment, so as to discharge the sludge into the ship at vary- 

 ing levels of the tide. A tramway will be laid along 

 the full length of the jetty connecting it with the 

 whole of the works. The surplus earth from 

 the excavations will be used in forming the banks 

 for the tramways, and in raising the general level of 

 the ground, which is now 6 or 7 feet below the level of 

 Trinity high-water. 



The quantity of sewage to be dealt with will amount 

 to about 90,000,000 gallons per day, and the quantity 

 of lime used in precipitation to 23 tons per day. 



ROYAL HORTICULTURAL SOCIETY. 

 At the last meeting of the Scientific Committee a 

 further discussion took place on the Plague of 

 Caterpillars, in the course of which Mr. O'Brien alluded 

 to the abundance of earwigs (Forficuld) this season. Mr. 

 Wilson drew attention to the local distribution of the 

 caterpillars. In one garden in his neighbourhood none 

 of the pests were found, while in others there was 

 scarcely a leaf left on the trees. At Wisley, Mr. Wilson 

 had found that exposure to east wind was associated 

 with the presence of the insects ; thus the trees in one 

 line of plums, fully exposed, were stripped of their 

 foliage, while in another line of the same variety close 

 by, on the same description of soil, but where the trees 

 were sheltered by a furze fence, not a leaf was injured. 

 From the editor of the Journal of Horticulture came a 

 letter written by a Guernsey grower detailing the course 

 of the well-known, or rather these two well-known 

 tomato diseases. The writer's plants were in a span- 

 roofed house, 60 X25 feet, and were affected last year, 

 when sulphur was applied without effect. After the 

 removal of the crop the grower took the precaution 

 to have the walls washed with lime, to renew the soil, 

 and adopted every known means to secure healthy 

 growth, but this year the disease is worse than before. 

 One grower was mentioned as having seven houses, 

 each 350 x 45 feet, decimated with the disease and not a 

 pound's worth of saleable fruit in them. Mr. W. G. 

 Smith referred to the full description and illustration of 

 the several fungi known to attack the tomato given in 

 the Gardeners' Chronicle, in 1881, November 12, and in 

 1887, August 6, October 1 and 29, by Mr. C. Plowright 

 and himself. Dr. Masters suggested the trial of sulphate 

 of copper in fine powder, mixed with precipitated lime, 

 and dusted over the foliage, as used in the French 

 vineyards. 



SCOTTISH METEOROLOGICAL SOCIETY. 

 At the meeting held on July 24th, Sir A. Mitchell in the 

 chair, Mr. H. N. Dickson read a paper on the " Tempera- 

 ture of the Air and Surface Water of the North Atlantic." 

 The paper gave the results of observations, in the 

 extreme months of February and August, of the area 

 of high atmospheric pressure called the Atlantic anti- 

 cyclone, of which the centre lies in about 35 north 

 latitude, and of the area of low pressure, whose centre is 

 situated between Greenland and Iceland. 



Dr. Buchan submitted a communication on the climate 

 of the Isle of Man, sent by Mr. A. W. Moore, Douglas. 

 In this paper, which contained the observations of fifty 



years, Mr. Moore arrived at the conclusion that the tem- 

 perature of the Isle of Man was more equable than that 

 of the surrounding coasts, being somewhat higher in 

 autumn and winter and similar in spring and summer; 

 that there was comparatively little frost and snow, but a 

 considerable amount of raw, damp weather, which to cer- 

 tain constitutions was more trying than a lower tem- 

 perature in combination with a dryer atmosphere, and 

 that its sunshine was much greater than in the sur- 

 rounding districts. Its winds were equal in strength and 

 frequency, though felt more in such an exposed place, 

 and its rainfall rather more than on the surrounding 

 coasts. 



Mr. Dickson read a note on the earth-currents on Ben 

 Nevis in connection with anti-cyclones, prepared by Mr. 

 R. T. Omond, in continuation of a series of observations 

 begun by Mr. Dickson himself in 1885. 



Dr. Buchan then read a paper by Mr. Rankin on St. 

 Elmo's fire, observed at the Ben Nevis Observatory. The 

 writer stated that up to the present only 1 5 cases of the 

 appearance of the fire had been recorded, and all occurred 

 at night. It was not at all improbable, however, that 

 the phenomena occurred during daylight, its faintness 

 rendering it invisible; indeed, on one occasion it had 

 been heard, the peculiar sound with which it was ac- 

 companied having been identified. Mr. Rankin had 

 connected the phenomenon with the prevailing weather 

 over north-western Europe. It occurred in times of 

 depression, when there was an electrical condition of the 

 atmosphere and a succession of cyclones. In almost all 

 cases the appearance of St. Elmo's fire meant not only 

 that a C3 T clone had passed, but that another was coming, 

 and thus one more had been added to the weather prog- 

 nostics quietly accumulating at Ben Nevis Observatory. 



THE ARTIFICIAL REPRODUCTION OF 

 VOLCANIC ROCKS. 



Translation of a Lecture Delivered by M. Alphonse 

 Renard, LL.D., at the Royal Institution. 

 ( Concluded froin p. 91.) 



LET us consider some of the conjectures about recent 

 volcanic products, suggested to us by this new pro- 

 cess, whose delicacy, certainty, and elegance have never 

 been surpassed in any other branch of natural science. It 

 has not only facilitated the verification and control of 

 hypotheses, but has guided them to the ultimate re- 

 markable discoveries, which we will enumerate. 

 Formerly the eye, even when aided by the strongest 

 magnifying glasses, could only detect fairly large mineral 

 crystals in the lava ; chemical analysis could often only 

 give the composition of the total mass ; the mineral con- 

 stituents were but guessed at ; the mineral texture of the 

 rocks remained a mystery ; there was no reliable 

 certainty as to the order in which the elements of the 

 mass had become solidified, or as to the various phases 

 of the crystals, their rough outlines, and primary forms, 

 or the aspect of the rock during its different stages of 

 development. Let us apply the microscope to the 

 examination of a thin slab of lava, rendered transparent 

 by polishing. As we have already seen, lavas may be 

 compared to a glassy mass, but whilst in our artificial 

 glass we endeavour to obtain a homogenous and limpid 

 product, the liquefied matter of the volcanoes already 

 contains at the moment of eruption differentiated 

 substances. The glass which unites them may be re- 



