May 27, 1909] 



NA TURE 



379 



in an extremely cold region. Silver fir, Ahics pcclinata, 

 grows well, and some large trees, one of which reaches 

 a height of 115 feet, date back to the year 1735. Two 

 horse-chestnuts, said to be the first planted in Scotland, 

 probably date back a few years earlier. Plantations of 

 the common larch are subject lo disease, but the Japanese 

 larch is healthy, and the Douglas fir thrives in sheltered 

 situations. 



The classic experiments by Moll concerning the absorp- 

 tion of carbon dioxide from the air will be familiar to 

 most botanists, more especially as illustrations are given 

 in Vines 's " Physiology of Plants." The experiment 

 where a leaf was inserted between two glass dishes has 

 been further investigated by Dr. V. Zijlstra, who has 

 embodied his results in a brochure on the transport of 

 carbon dioxide In leaves. He finds that when part of a 

 leaf is placed in an atmosphere devoid of carbon dioxide, 

 and the adjacent part of the leaf is covered, then the carbon 

 dioxide formed in this part of the leaf in respiration diffuses 

 through the leaf, and a band of starch is formed beyond 

 the screen. The band varies from 5 mm. in the dahlia 

 to 2-5 cm. in wheat, while through the leaves of Eichhornia 

 and Pontederia the gas can diffuse much more readily. 



In the May number of Man Dr. F. C. Shrubsall describes 

 two crania and some long bones from ancient ruins in 

 Rhodesia. The skulls seem to be of the Bantu, not of the 

 Bushman, type ; in other words, they belong to a negro 

 race similar to the inhabitants of Rhodesia at the present 

 day. The position in which these remains were found 

 seems to Indicate that they were coeval with the buildings 

 near which they were discovered. While this does not, 

 of course, prove that negroes were the builders of the 

 famous ruins, it is significant to note that the remains 

 do not belong to any of the more northern races. The 

 fact that the bones were associated with valuable gold 

 ornanienis precludes the supposition that these negroes had 

 been enslaved by the foreigners, w^ho, according to one 

 theory, were the builders of these remarkable structures. 



We have received copies of two fasciculi, one dealing 

 with Oligochajla and Hirudinea, and the other with Nema- 

 todes, (iordiida?, &c., of Die Susswasserfaiina Detttschlaitds, 

 eiiw E.xl;ursionsfauna (Jena : G. Fischer). The parts (of 

 which those before us are respectively numbered 13 and 15) 

 are sold separately, at a price varying between one and two 

 shillings each, and they are issued in narrow duodecimo 

 form, so as to be convenient for carrying in the pocket. 

 Each part is, moreover, written by a specialist, and 

 sufficiently, although diagrammatically, illustrated, and the 

 whole work appears, therefore, to be admirably adapted 

 for the purpose for which it is intended, namely, as a 

 companion for the field-naturalist. 



The report of the Bombay and Alibag observatories 

 for the year 1908 has been received. White ants cause 

 much damage at the Colaba (Bombay) Observatory ; glass 

 insulators filled w'ith kerosene have been provided for the 

 presses containing the records, but it is doubtful if they 

 will prove efficacious. The rainfall for the year amounted 

 to 5354 inches, being 21-62 inches below the average for 

 1873-96; of that amount, 52-70 inches fell between June 

 and September inclusive, the period of the south-west 

 monsoon. Milne's seismograph registered forty-eight 

 earthquakes, besides several small movements ; great dis- 

 turbances occurred on January 11, February 9, August 20, 

 and November 2. A table prepared in accordance with 

 the suggestion of the International Commission for 

 Terrestrial Magnetism, representing the magnetic character 



NO. 2065, VOL. 80] 



of each day, shows that there were 135 calm days, the 

 remaining days of the year showing small or larger dis- 

 turbances ; six of the latter were days of great disturb- 

 ance. The mean declination was 1° 2' east. 



The ballistic galvanometer method of measuring quanti- 

 ties of electricity has proved so convenient and flexible 

 that it has been used to determine changes of magnetic 

 induction in cases to which it was not strictly applicable. 

 .According to the simple theory of the instrument, the 

 whole of the electricity must have passed through it before 

 the moving part of the instrument has had time to move 

 appreciably from its position of rest. Prof. O. B. Pierce, 

 of Harvard, has investigated the behaviour of a d'Arsonval 

 galvanometer the period of swing of which was raised to 

 ten minutes by attaching to the coil a circular disc with 

 a weighted rim. He finds that the simple theory is still 

 applicable to such an instrument, and has by means of it 

 measured the changes of magnetic induction through large 

 electromagnets. His memoir forms No. 11 of vol. xliv. 

 of the Proceedings of the American .Academy of .Arts and 

 Sciences. 



Some comparison tests between the new F^ry spiral 

 pyrometer and a standardised thermoelectric F^ry radiation 

 pyrometer are recorded in Engineering for May 14. The 

 spiral pyrometer has -the advantage over other types of 

 radiation pyrometers in that it is self-contained. The 

 instrument consists essentially of a very small spiral made 

 of a strip of two metals having very different coefficients 

 of expansion, and having a pointer attached. The spiral 

 unrolls when heated, and the pointer travels over a scale 

 indicating the temperature of the furnace. Rays coming 

 from the furnace are reflected by a concave mirror and 

 sent to the spiral, any radiation passing through the spiral 

 being reflected back to it by means of a second small 

 mirror. The whole is contained in a lube furnished with 

 a focussing arrangement by means of which the observer 

 directs the instrument towards the furnace and obtains 

 an image of it. Adjustment of the zero of the instrument 

 is easily effected. The tests were conducted by Mr. G. C. 

 Pearson in the retort-house of the Birmingham Gas 

 Works, and ranged between 845° C. and 1260° C. The 

 greatest difference between the readings of the two instru- 

 ments amounted to 10° C. at 930° C. ; the mean of twelve 

 readings shows the spiral pyrometer to be reading about 

 1° C. in excess of the thermoelectric pyrometer. The 

 maker's claim of an accuracy within i per cent, or 2 per 

 cent, is thus amply justified. The instrument is being 

 constructed in this country by the Cambridge Scientific 

 Instrument Company. 



.A siiRiES of special demonstrations on the use of micro- 

 scopes, and various microscopic appliances and accessories, 

 has been held during the past week or so at the London 

 depot, 9-15 Oxford Street, of Mr. Ernest Leitz, of 

 Wetzlar. It is generally known that this firm was prac- 

 tically the pioneer in the production of cheap microscopes 

 and objectives of Continental make, and an inspection of 

 the apparatus now shown clearly indicates that, though a 

 low standard of price is maintained, the apparatus pro- 

 duced is of a very high class. It is interesting to note 

 that in the production of the new types of microscope 

 stands the firm is being largely influenced by English 

 ideas of design ; the result is a type of instrument which 

 combines to a considerable extent the Continental horse- 

 shoe foot and the much more stable English tripod foot. 

 Could Mr. Leitz carry this innovation somewhat further, 

 he would be in a position to produce an instrument which 

 in point of design and for general stability and convenience 



