November 13, 1902] 



NA TURE 



winged flies, " cow-bees," " wild-bees" and other Hymenoptera 

 suffered severely, but other groups escaped practically un- 

 harmed, and there is no doubt that the dust has had little, if 

 any, effect on the insect pests. The dust, in fact, destroyed not 

 the pests, but the useful two-winged flies, &c, which prey on 

 the caterpillars and other pests, so that in this way the volcanic 

 ash has tended to disturb the balance of nature. Its effect is 

 declared to be possibly a harmful one except in the case of the 

 present corn crop, as the dust, lodging in the heart of the young 

 plants, prevents the worms eating into the young leaves. 



The third part of the general report and statistics [for 1901 

 relating to the output and value of the minerals raised in the 

 United Kingdom, the amount and value of the metals pro- 

 duced, and the exports and imports of minerals, edited by 

 Prof. C. Le Neve Foster, F. R.S., has been issued as a Blue- 

 book. The first year of the new century has an unfavourable 

 record so far as the mineral industry is concerned. Quantities 

 have been smaller and prices lower. The value of the coal 

 raised during 1901 represented SS'S per cent, of the total 

 mineral output for the year, but was six million tons less 

 than the previous year, this being the first interruption in the 

 steady rise since the great strike of 1893. Although the output 

 of coal was less than in 1900, more persons were employed in 

 and about the mines. The output of iron ore has continued to 

 fall since 1899, and the diminution of if million tons in 1901 

 represents 12J per cent, of the quantity raised in the previous 

 year. The comparative unimportance of the metallic ores, 

 other than iron, is easily understood when it is stated that their 

 value only amounts to 800,000/., which is just half the 

 value of the sandstone and far less than that of the lime- 

 stone, the slate or the igneous rocks. The oil-shale mines of 

 Scotland yield a product of greater money importance than the 

 tin mines of Cornwall. 



We have received a report on observations of the tidal cur- 

 rents and undercurrents in the Strait of Dover, published by 

 the Hydrographic Department of the Admiralty. The report 

 consists of two parts. The first part contains observations 

 made by Mr. M. F. J. Wilson, engineer-in-charge of the ex- 

 tension works at the Admiralty pier at Dover, with the object 

 of ascertaining whether a report by divers, that the tidal stream 

 changed its direction at the bottom a very long time before the 

 surface, was correct ; the result shows that the report was un- 

 founded. The second part contains observations taken by 

 Captain A. M. Field in H.M.S. Research in the Dover channel, 

 in order to test the accuracy of conclusions suggested by the 

 observations made by Captain W. V. Moore in 1896, to the 

 effect that on the English side of the Strait the water below a 

 certain depth was still, while the surface current was strong. 

 The earlier observations are shown to have been erroneous, as 

 the tidal streams run to the bottom of the Strait. 



Terrestrial Magnetism and Atmospheric Electricity for Sep- 

 tember contains a biographical sketch of General Sir Edward 

 Sabine, accompanied by a photographic reproduction of the 

 portrait belonging to the Royal Society. 



The Italian Meteorological Office has forwarded us Nos. 4-6 

 of its Bollelino mensuale, or monthly weather review, containing 

 a note on Count Almerico da Schio's attempts at aerial navigation. 

 The form preferred by Count da Schio is a fish-shaped balloon 

 with flexible keel, the Buchat motor yielded 12 horse-power, 

 and the work of construction has been carried on in a private 

 workshop. 



A paper by Dr. Loria (Genoa), on the origin and develop- 

 ment of geometry prior to 1S50, has been translated in the 

 Monisl by Dr. G. B. Halstead. So far as it is possible to sum 

 lip briefly the author's conclusions, it would appear that : (l) 

 NO. I724, VOL. 67] 



While it is impossible to determine the first origin of geometrica 

 research, it is certain that the Assyrians and Babylonians studied 

 many important geometrical problems. (2) The geometry of 

 the Egyptians was of far greater importance, and had a 

 particular tendency towards practical applications. (3) Thales 

 and the Ionic period represent the twilight preceding the dawn 

 of Greek geometry. (4) The " golden period " of Greek 

 geometry came within the Alexandrine epoch, its most con- 

 spicuous representatives being Euclid, Archimedes and Apol- 

 lonius. (5) In the list of Greek geometers, Heron of Alexandria 

 and Claudius Ptolemy play a prominent part, and the "silver 

 period " of Greek geometry was notable for the appearance of 

 Eutocius and Proclus, and especially Pappus. (6) The 

 ascendency of the Romans and the subsequent middle ages 

 represent a period of decadence for geometry. (7) The renais- 

 sance of mathematics commenced with the appearance of 

 Leonardo Fibonacci (1200 circa), and before the end of the 

 sixteenth century we note the names of Tartaglia, Cardan and 

 Ferrari. (8) The primacy of mathematics in France was 

 attained by the appearance of Viete, Mydorge, Pascal and 

 Desargues; Henry Savile of Oxford and Kepler also belong 

 to this period. (9) A new era was introduced by the analytical 

 methods of Fermat and Descartes. (10) In the next section, 

 Prof. Loria traces the influence of infinitesimal methods on the 

 study of geometry, and (11) considers in particular the de- 

 velopment of the study of curves and surfaces in three 

 dimensions. 



M. G. Lippmann, writing in the Journal de Physique for 

 October, describes ingenious methods for verifying whether a 

 ruler or sliding bar is rectilinear, and for fixing a collimator in 

 the focal plane of a lens or telescope objective. For the first pur- 

 pose he attaches one telescope with cross wires to a "chariot" 

 which runs along the ruler, and observes the image of the 

 wires in a second telescope which is fixed. If the two systems 

 of cross wires remain coincident as the chariot runs along the 

 ruler, M. Lippmann concludes that the ruler is rectilinear, and 

 the only exception that could be made to this inference would 

 be if the surface of the ruler formed a series of waves of 

 length equal to the wheel-base of the chariot. To fix the col- 

 limating wires in the focal plane of a lens, M. Lippmann now 

 fixes the auxiliary telescope to the chariot in such a way that it 

 can be displaced parallel to its axis, and he uses it to view the 

 wires in the telescope to be tested. If these remain unchanged 

 in position when the auxiliary telescope is shifted, the collimation 

 is correct ; if not, the shift of the image determines the amount 

 by which the wires must be adjusted in order to bring them into 

 the focal plane of the lens. The chariot runs on a sliding piece 

 which has been previously tested by the first method. 



Mr. Basil Thompson, in his "Notes upon the Antiquities 

 of Tonga" (Journ, Anth. Inst., xxxii. p. 81), describes the 

 famous trilithon, or Haamonga. He inclines to one traditional 

 account which relates that it was erected by Tui-ta-tui in the 

 latter half of the fourteenth century. It was built for him to 

 sit upon during the Kava ceremonies out of reach of his people, 

 as he so dreaded assassination. 



Several years ago, Mr. Henry Balfour published an im- 

 portant memoir on the musical bow, and in the current Journal 

 of the Anthropological Institute (vol. xxxii. p. 156) he describes 

 a superficially similar instrument, the goura, which Frobenius 

 and Ankermann have confused with the musical bow proper. 

 The goura is a bow-like instrument ; one end of its string Is 

 fastened to a flattened quill, the other end of which is fastened 

 to the bow, and the string -is thrown into vibration through the 

 medium of the quill, which is caused to oscillate by being blown 

 upon. Those musical bows which have no resonator are held 

 to the mouth when playing in order to increase .the 1 sound, but 



