394 



NA TURE 



[February 22, 1694 



such as the following : — {a) Specimens of the natural history 

 and geology of the forest district — the quadrupeds, birds, 

 fishes, reptiles, insects, trees, wild flowers, fungi, fossils, &c. 

 (/') Instructive preparations to illustrate the variety of form 

 colour, structure, habits, transformations, and development, &c.. 

 of the above, with examples of galls and other plant disease 

 and injuries, (f) The antiquities of the forest districts; illus- 

 trations of the camps, and other earthworks ; prehistoric im- 

 plements and other remains, &c. {d) Plans, maps, photo- 

 graphs, pictures, models, &c. relating to the district ; illustra- 

 tions of the history of the forest, and its scenic beauties ; the 

 archil:es:iural and archseological features of the di>trict, &c. 

 (f ) A small collection of books — guides, histories, manuals of 

 natural history, &c. — useful to those wishing to learn something 

 about the district before taking rambles therein. A local 

 museum of the kind proposed would be a source of interest 

 and utility to all lovers of nature, and might be made of con- 

 siderable educational value. 



In the early part of this week a very severe frost set in over 

 the midland, eastern, and southern parts of England, accom- 

 panied by piercing easterly winds ; the night minima in the 

 shade fell to i6° at Loughborough, and to about 25° at 

 Shields ; while in London the temperature on the grass 

 was as low as 14°, and fog occurred over the inland 

 parts of England. These conditions were due to an area 

 of high atmospheric pressure which lay over Denmark, the 

 Netherlands, and south of Scandinavia, where the barometer 

 readings were as high as 30*6 inches, with lower readings 

 further south. But our extreme north and west coasts were 

 under the influence of low pressure areas, and a south-westerly 

 gale was blowing at Stornoway on Monday evening ; conse- 

 quently the temperature in these parts was higher. 



In Dr. Wild's Annalen des Phyiikalischen Central Ohserva- 

 torinms for 1892, just received, it is recorded that at Wer- 

 chojansk, Lat. 67° 34' N., Long. 133° 51' E., the temperature 

 fell in February to — 69°'8 C. or - 94°'6 F. This is 

 absolutely the lowest temperature of the air hitherto observed 

 anywhere on the surface of the earth. 



In Ciel et Terre of the 1st inst. M. A. Lancaster contri- 

 butes an interesting paper " On the commencement and end of 

 winter," as determined by the first and last occurrence of snow 

 and frost at Brussels. He gives tables showing these dates for 

 sixty-one years, from 1832-3 to 1S93-4 (the data for the first and 

 last of these years being incomplete). On an average, the first 

 frost occurs about November 10, and the first snow about five 

 days later, while the first frost of much intensity (below 20° F. ) 

 occurs about six weeks afterwards. At times these phenomena 

 occur much earlier or later ; the first frost occurred in 1864-5 ^"^ 

 in 1881-2 on October 5, while in 1877-8 no frost occurred until 

 December 10. The last frost occurs, on an average, about April 

 4 ; in 1885-6 there was a frost as late as May i, while in 1835 6 

 the thermometer did not fall below 32'^ after February 24. The 

 fall of snow is much more irregular ; it fell seventeen times in 

 May, and once in June (in the year 1866). A paper of a 

 imilar nature was published for Sweden in 1880, by M. Hilde- 

 brandsson. 



The practice of spraying fruits with certain mineral com- 

 pounds, such as salts of copper and arsenic, to destroy insects and 

 fungi, has called out discussion in regard to the ripened (ruit after 

 such spraying, and its fitness for food. The first condition for 

 intelligent discussion of any subject is to know the facts in the 

 case, so experiments have been made on the matter at the State 

 Agriculture College, Michigan, and Bulletin No. lOl contains 

 the results. In these experiments, extending over two years, the 

 minerals used in spraying the fruits were lound in appreciable 

 quantities in every instance, though the amount was small in all 



NO. T269, VOL. 49] 



cases except when the spraying had been purp'isely excessive. 

 The question naturally arises whether the sprayed salis merely 

 adhere to the surface or penetrate the substance of the Irui'. Ex- 

 periments made to test this showed that while most of the copper 

 salts, in the case of a solution containing copper sulphate, ad- 

 hered to the surface of pears sprayed with the solution, a portion 

 found its way into the body ol the fruit. Dr R. C. Kedzie, 

 who has made the analyses, remarks that the use of poisons in 

 horticulture is largely in excess of the amount required for a 

 fungicide. One-half or even one-third of the amoun usually 

 employed would probably give as good results. To be on the 

 safe side, no fruits should be sprayed with solutions of mineral 

 salts during the period of ripening, for though the amount found 

 in a single pound of fruit may be very small, repeated doses of 

 the poison might produce slow poisoning. 



The new theory of light-sensation devised by Christine L, 

 Franklin, and intended to avoid the difficulties involved in 

 the acceptance of the two chief theories in the field at present, 

 known as Helmhohz's and Hering's theory respectively, is ex- 

 pounded in ihe last two numbers of Mind. While the Young- 

 Helmholtz theory supposes that the judgment picks out of a 

 mixture of colours all the even red-green-blue sensations, and 

 deceives itself into thinking them to be a new sensation called 

 white, the new theory assumes an independent retinal process as 

 ground for the latter sensation, therein agreeing with Hering's 

 theory. Bat while Meringsupposesthat some parts of the spectrum 

 produce construction, and others destruction of the tissue of the 

 retina, Miss Franklin considers that the sensations of the black- 

 grey- white series must be regarded as the fundamental ones, and 

 attributed to the dissociation of certain molecules, which she 

 provisionally calls the grey molecules. The atoms thus dis- 

 sociated have different periods of vibration, and in the more 

 highly developed visual organs — those capable of colour- 

 sensations — these colour-atoms differ in behaviour according to 

 the wave-length of the light beating upon them. Thus some 

 atoms would only be torn off" by red light, and would give rise 

 to the sensation of red. The prevalence of such colour molecules- 

 would coincide with the predominance of the structures known 

 as cones in the fovea of the retina, while the " rods " are en- 

 dowed chiefly with grey molecules. This is simply translating 

 into the language of the theory the well-known fact that the 

 colour sense is chiefly confined to the centre of vision, as any- 

 body may prove by looking at a coloured object through the 

 corner of the eye. This distribution, says Miss Franklin, offers 

 a perfect analogy with that of the organs of hearing. In the ear 

 we have a very simple apparatus for hearing noise only, and 

 also a highly differentiated structure for the discrimination of 

 notes of various pitches. 



In 1881 M. Blondlot gave the results of some experiments he 

 had made on the velocity of propagation of Hertzian waves. 

 The velocity was determined by calculating the period of the 

 electrical vibiations from the dimensions of the resonator,, 

 and measuring experimentally the wave-length. The results 

 obtained, while they indicated that the velocity is always 

 approximately that of the propagation of light, showed that as 

 the wave-length increased the velocity diminished. In a note, 

 communicated at a recent meeting of the Academie des Sciences 

 (Paris) {Comptes Rendus, No. 6, 1894), M. Mascart has shown 

 that a more accurate calculation of the frequency gives a 

 remarkable agreement between the different experiments. In 

 this note the author gives the formula for the self-induction of 

 a rectangle of wire, and applies it to the reduction of M. 

 Blondl-.t's observations. He finds that the values obtained 

 for the velocity of propagation show no systematic variation 

 with the wave-length within the limits of observation, that is,, 

 between wave-lengths of 9 and 35 metres. The mean of all i 

 the experiments gives the value 303,200, kilometres per second 



