May 1, 1000.] 



KNOWLEDGE. 



103 



Granite, in the natural processes of disintegration, be- 

 comes sufficiently broken up. the Felspar and Mica are 



A Section of Orauitc from Skiddaw. x 45. (Rcproduceil i| from a 

 slide in the Woodwardian Museum. Cambridge, by kind perinifsiou 

 of Prof. T. McKenny H\iglics, F.K.8.) A, Quartz; B, Felspar; 

 c, Mica. 



exposed to the action of the atmosphere, and in conse- 

 quence are decomposed, and from the products of their 

 decomposition a fertile soil is formed. 



A second very important factor in the fertility of the 

 soil is the climate. It is the experience of planters 

 and farmers all the world over that in a propitious 

 climate almost any soil is fruitful, a fact partly though 

 not entirely due to the direct effect of a favourable 

 climate upon the vegetation. The effects of different 

 degrees of rainfall, temperature, sunshine, and other 

 influences included in the term " climate," upon the 

 soil are exceedingly diverse, and very imperfectly under- 

 stood. In some parts of the world where the climate 

 changes very suddenly in passing between two places 

 situated within a few miles of one another, corresponding 

 changes in the fertility of the soil appear to be due 

 entirely to climatic differences. In the central plateau 

 of Ceylon, for instance, there are several remarkable 

 isolated peaks rising to 2,000 or 3,000 feet above the 

 general level of the country. The eastern slopes are, as 

 a rule, preferred by tea planters, because the soil is 

 found to be more fertile than on the western side. The 

 difference is undoubtedly to be attributed to the climate, 

 though the precise manner in which the soil is affected 

 by it is not well understood. The western slopes of 

 these hills are subject at certain seasons to the biting 

 winds of the South-west monsoon, and are very con- 

 stantly enveloped in mist; on the opposite side the 

 winds of the North-east monsoon arc- less injurious to 

 vegetation and the sun is much less obscured by cloud. 

 When the slopes were covered by virgin-forest these con- 

 ditions caused a more luxuriant vegetation to exist on 

 the eastern faces than on the western, and in conse- 

 quence the soil on that side was more copiously en- 

 riched by humus one of the most important contributors 

 to fertility in a soil. This is by no means the only way 

 in which the soil is affected by climatic differences. 

 These have an important effect upon the decomposition 



II From a mii-ropliotograiih kindly taken for this paper b)' Mr. 

 H. Stanley Jevons, P.O. 8. 



of the soil-particles continually t<iking place in order to 

 make up the delicicniios caused by the demands of 

 existing and increasing vogot^ttioii. To what extent and 

 in what manner the climate inlluenccs this process are 

 questions which have a-s yet received no very clear 

 answers, and a consideration of them is too wide for our 

 present limits. Rain is also an important fertiliser of 

 the soil, for it adds to it the " impurities " swept down 

 out of the atmosphere, and in many cases brings down 

 solid matter from the land at higher levels. It ha.s been 

 proved that a very large proportion of a plant's mineral 

 needs can be .satisfied by the substances chiefly in the 

 form of dust thus carried down from the atmospjievc. 



The capability of a soil to support vegetation is also 

 in a very important manner due to its power of retain- 

 ing part of the water falling upon it as rain. This 

 depends partly upon the size of its mineral particles 

 and also upon the amount of humus (vegetable mould) 

 it contains. Humus has a very strong avidity for water, 

 and largely increases the water-holding power of the .soil. 

 It has been said, probably with truth, that, from the 

 point of view of the plants it supports, the most im])or- 

 tant property of the soil is its behaviour towards moisture 

 — in other words, the relative amount of water it is able 

 to hold by capillarity. The characters of the water thus 

 retained, and some interesting facts concerning the food 

 substances held in solution, remain for further con- 

 sideration. 



A TEMPLE OF SCIENCE. 



By W. Alfred Park. 



Among the many museums and galleries, filled with the 

 priceless treasures of past generations, with which 

 Florence abounds, and which render the city of Dante a 

 veritable " Mecca " alike to the artist and the student, 

 perhaps none offers a greater interest to the scientific, 

 and more especially the astronomical, visitor than that 

 Temple of Science known as the " Tribuna di Galileo." 

 This richly decorated hall, in which are worthily en- 

 shrined some of the most interesting and valuable 

 scientific relics relating to the life and work of Galileo, 

 and which vies in point of interest with the picturesque 

 old tower known as Galileo's Observatory, described 

 by me in a former number of Knowledge,* forms part 

 of the Museum of Physical Science, and was inaugurated 

 in 1840, on the occasion of the assembly at Florence of 

 Italy's principal scientific men. Dedicated, as it is, 

 to the memory of the great Tuscan astronomer, it was 

 but fitting that the structure itself, as well as the paints 

 ings, sculptures, and mosaics with which it is so richly 

 adorned, should be representative of the best talent of 

 Tuscany ; and that the artists entrusted with the 

 erection and decoration of this memorial to their illus- 

 trious compatriot succeeded in worthily acquitting 

 themselves of their ta.sk, may be seen from the accom- 

 panying photograph. 



On every side are depicted interesting episodes in the 

 life of Galileo, from the time when, as a young student, 

 he watched the swinging lamp in the Cathedral of 

 Pisa, to the time when, old and blind, and in the re- 

 tirement of his villa at Arcctri, he dictated the account of 

 his researches to his two celebrated pupils, Torricelli and 

 ■Viviani; while in the centre of the apse, dominating 

 the whole, stands Professor Costoli's statue of the great 

 astronomer. The painting in the ceiling immediately 



* See Knowlkdoe for July, 1899, p. 157. The tower is now the 

 property of Count I'aolo (ialletti. 



