June 1, 1889.] 



♦ KNOW^LEDGE ♦ 



173 



herbals of Diosoorides and Brunfels to the system of Liniiieus or 

 Jussieu; the other and nobler line rises in Virgil's song of living 

 nature, runs through the keen yet simple records of naturalists 

 like those of Selborne and Walden, and culminates in the 

 monumental volumes of the greater naturalist of Down. 

 It is in the school, or rather garden, of Darwin, viewed 

 both as the last of the old-world naturalists, and as the first of 

 evolutionists and physiologists, that our modern "introduction to 

 botany " must begin ; studies in the herbarium of the systematist 

 and the special laboratories of the physiologist, anatomist, and 

 microscopist may follow thereafter as occasion requires. For the 

 age of mere analysis, guided only by the love of incessant novelty, 

 or even by that of unity amid details, is ending ; the student may 

 now approach the service in a new spirit, since he can interpret its 

 literature as but the incipient record of that vast drama of the 

 evolution of life at which it is his rare good fortune to be an 

 awakening spectator. 



In hi.s summary of the " Darwinian theory," Mr. Geddes 

 refers too briefly to the existing differences between the 

 neo- Lamarckian school, to which Herbert Spencer is lending 

 his support, and the school of which Professor Weismann is 

 the chief representative, and which contends tliat the 

 theory of the inheritance of acquired characters is not 

 needed to explain the phenomena of the organic world — in 

 other words, that changes acquired by the individual are 

 never transmitted. We may, however, look for a full dis- 

 cussion of this when the article on " Evolution " is reached. 

 Among the historical articles, we may call special attention 

 to that on the " Celts " from the competent pen of Professor 

 Ehys, who, with his true sense of historic continuity, deals 

 with the persistence of pre-Celtic non- Aryan races and their 

 influence in divers ways upon later settlers. The maps 

 and woodcuts throughout these volumes are perfect in their 

 clearness, and we hope that an undertaking into which the 

 best workmanship possible is put will meet with the success 

 which such efforts deserve and seldom fail to win. 



Ed. Clodd. 



The Juno number of Harper's Mwjuzine cimtains an 

 interesting article by Professor George Darwin on the 

 planet Saturn and his ling system. 



At a recent meeting of the Meteorological Society, Mr. 

 W. II. Dines gave an account of .some experiments made to 

 investigate the connection between the pressure and velocity 

 of the wind. The pressure plates were placed at the end of 

 the long arm of a whirling machine which was rotated by 

 steam-power. Experiments were made with about twenty- 

 five different kinds of pressure plates. The pressure upon a 

 plane area of fairly compact form is about l.V lbs. per square 

 foot at a velocity of 2 1 miles per hour ; and as the pressure 

 varies with the square of the velocity, a pressure of 1 lb. 

 per s(|uaro foot is causi'd by a wind of a little more than 

 17 miles per hour. The pressure upcm tlu; same area is 

 increased by increasing the perimeter. The pressure upon 

 a j -foot plate is proportionally less than that upon a plate 

 either half or double its size. The pressure upon any 

 surface is but slightly altered by a cone or rim projecting at 

 the back — a cone seeming to cause a slight increase, but a 

 rim having apparently no olfect. 



What causes the blue flame produciid when salt is thrown 

 into a coal fire 1 This is a ([ucstion that is frequently asked, 

 and has bo(^n answered many ways. It must bo remembered 

 that salt or sodium chloiido consists of only two elements — 

 sodium and cblorine. Sodium is known to be the great 

 producer of yellow flame, and therefore it is quite reasonable 

 to suppose that the chlorine has to do with the blue flame. 

 Some recent experiments by Mr. N. Leonard support this 

 view. He shows that the blue flame is also produced by 



some other metallic chlorides, but that it is not produced by 

 other compounds of sodium. It is further demonstrated 

 that certain compounds of chlorine containing carbon, such 

 as, chloroform, chloride of carbon, (fee , also produce a blue 

 flame when thrown in the fire. This has led to the con- 

 clusion that when salt is thrown on a coal fire, the chlorine 

 forms a compound or compounds with the carbon in the 

 coal, which by decomposing gives rLse to the blue flame. 

 This conclusion finds support in the fact that when salt is 

 thrown on to a red-hot body containing no carbon, platinum 

 for instance, the blue flame is not produced. 



A VALUABLE LIBRARY. 

 In a street leading from Chancery Lane into Staple Inn 

 is an institution which deserves to be better known. It 

 is the free scientific library of the Patent Oflice. Mounting 

 a high staii'case you enter a hall with a series of bays 

 on either side. In these, and in adjoining rooms, there 

 are nearly 100,000 volumes arranged by subjects under the 

 headings — Chemistry, Physics, Astronomy, Biology, Agi'i- 

 culture. Metallurgy, and so on. The visitor, after merely 

 writing his name and address in a book at the door, is free 

 to go anywhere, and take down any book he likes. The 

 library is particularly rich in scientific periodictils, both 

 English and foreign. The current numbers are laid out for 

 inspection on two large tables, an advantage which the 

 reader at the British Museum does not enjoy. The num- 

 ber of visitors to the institution shows rapid increase, 

 e.specially since the hour of closing was made 10 p.m. instead 

 of 4. The librarian reports that there were 80,000 readers 

 last year. 



THE FACE OF THE SKY FOR JUNE. 



By Herbert Sadler, F.R.A.S. 

 POTS of any size are still of verj' rare occur- 

 rence on the sun's disc. During the mouth 

 of June there will be no real night through- 

 out the British Islands. On the morning 

 of the 28th there will be an annular eclipse 

 of the sun, which, however, will not be 

 \ isible at Greenwich. The line of centnvl 

 eclipse enters Africa, near Walfisch Bay, on the west coast, 

 and crosses the southern portion of the Continent till just 

 south of the river Rovuma on the east coa^t ; after that 

 its track is entirely across the Indian Ocean. Minima 

 of the Algol type variable 5 Libra; (cf " The Face of the 

 Sky for April") occur on the 3rd at lOh. 7m. 1'..m., on the 

 10th at 9h. 4lm. p.m., on the 15th at 9h. 15m. p.m., and on 

 the 24th at 8h. 50m. p.m. Mercury sets nearly one hour 

 and three- (|uartors after tlie sun on the 1st of the month, 

 with an apparent diameter of 9i ', and a northern declina- 

 tion of 2 1;^^ and will 1x3 fairly well j>laced for observation 

 during the first week in June. After that he rapidly 

 approaches the sun, coming into inferior conjunction at 

 llh. A..M. on the 19th. Subsequently he becomes a morning 

 star, but rises in very bright twilight. He does not approach 

 any naked-eye star veiy closely. Ventis is a fine object 

 in the morning sky, being at her greatest brilliancy on the 

 Gth. On the 1st she rises at 2h. 28m. a.m., having an 

 apparent diameter of 42 ', and a northern declination of 

 11.',°. On the last day of the month she rises at Ih. 30m. 

 A.M., 2h. 18m. before the sun, with a northern declination 

 of 15° 20', and an apparent diameter of 24''. On the 

 morning of the 11th she will be very close to the Gth magni- 

 tude stiir 31 Arietis. Mars is absolutely invisible, being in 

 conjunction with the sun on the morning of the ISth. IKving 

 to his extreme southern declination, below 23° south through- 

 out the month, Jupiter, though he comes into opposition 



