July 20, 1882] 



NATURE 



275 



wonderful avenue of snake trees, when my attention was 

 arrested by a noble group of palms, including nearly all 

 those indigenous to the island, and a number of foreign 

 representatives of this noblest of tropical trees ; all 

 festooned with masses of flowering creepers, and adorned 

 with graceful ferns growing at their base. Another 

 similar, but larger and more beautiful group of palms 

 stands at the further end of the avenue. Here the path 

 divides and leads on the left to a little eminence, on 

 which the director's bungalow stands. This charming 

 residence is, like most of the villas of Ceylon, a low one- 

 storied building, surrounded by a verandah, the projecting 

 roof of which is supported by a row of white pillars." 

 . . . The villa stands on the highest point of the garden, 

 which covers an area of 150 acres, and overlooks the 

 noble Mahawelli River, which encircles it on three sides. 

 Its position and climate are unusually favourable for the 

 cultivation of all the wonders of the Ceylon flora. 



" In four days spent in Peradenia," says Prof. Haeckel, 

 " I learnt more of the life and nature of the vegetable 

 world than I should have acquired by as many months of 

 close botanical study at home. I can never be grateful 

 enough to my good friend Dr. Trimen for his hospitality 

 and the rich stores of learning which he placed at my 

 service ; the days spent in his bungalow were among the 

 most fruitful of my life. 



'• Another English botanist, Dr. Marshall Ward, was at 

 Peradenia at the same time as myself; he had pursued 

 his studies for the most part in Germany, and bore the 

 official title of 'Royal Cryptogamist.' He had been 

 sent here two years previously by the English govern- 

 ment to study the coffee leaf disease which for many 

 years has raged with inceasing violence in the coffee- 

 plantations of Ceylon, and has in great measure destroyed 

 this valuable source of revenue to the island. Dr. Ward 

 made many valuable observations and experiments on 

 the natural history of the microscopic fungus, which 

 contains the germ of the disease ; but unfortunately 

 he did not succeed in discovering any radical remedy 

 for it. Instead, therefore, of receiving the gratitude 

 due to him for his assiduous labours, he found him- 

 self violently taken to task by the press, and especially 

 by the coffee planters. As if the hundreds of European 

 naturalists engaged at the present time in investigat- 

 ing the nature and causes of similar plant epidemics 

 should all be expected to discover a remedy for the disease 

 they are studying ! That this is seldom successfully done 

 is a well established fact, and no axiom is more devoid of 

 truth than that current in what are called ' cultivated 

 circles,' that ' every disease has its cure.' 



" It would lead me too far, and would weary my 

 readers to no purpose were I to attempt a mere verbal 

 description of the botanical paradise of Peradenia ; even 

 the drawings and water-colour sketches which I there 

 made give a very inadequate idea of its beauties. 

 Unlike most of our botanic gardens in Europe, the 

 plants are not disposed in stiffly laid out beds, but are 

 arranged with a regard to aesthetic effect, as well as to 

 scientific classification. The principal groups of trees 

 and the plants of kindred families are gracefully divided 

 by smooth lawns of turf, and good paths lead from one to 

 the other. In a more retired part of the park are the less 

 attractive and more useful growths of both hemispheres, 

 the seeds, fruit, and shoots of which are distributed 

 among the gardeners and growers of the island. In this 

 way the garden has been for many years of great practical 

 utility as a centre of experiments and a garden of 

 acclimatisation." 



We must conclude our extracts with a suggestion from 

 Prof. Haeckel which seems worthy of notice. He says : 



" The singularly favourable climatic and topographical 

 conditions of the Garden of Peradenia would seem to fit 

 it for a wider sphere of scientific usefulness as a botanic 

 station. In the same way that zoological students are 



now provided with invaluable means of assistance in the 

 prosecution of their studies by the establishment of zoo- 

 logical stations on the sea-coast (at Naples, Roscoff, 

 Brighton, Trieste, &c.) might young botanists in such a 

 botanic station as Peradenia learn and accomplish as 

 much in one year as they would in ten years under less 

 favourable circumstances. Hitherto the tropical zone, 

 the richest of all in materials for study, contains no such 

 institution. If the English Government would establish 

 and maintain a botanic station at Peradenia and a zoo- 

 logical station at Galle, she would add an important item 

 to the services bestowed on science by her Challenger 

 Expedition and other similar scientific undertakings ; and 

 she would once more put to shame those States'of Conti- 

 nental Europe who can find no more useful or beneficial 

 way of spending their money than in the manufacture of 

 breech-loaders and cannon." 



KCENIG'S EXPERIMENTS IN ACOUSTICS 1 

 II. 

 T N a preceding article it was recounted how Koenig has 

 *■ applied the principle of the wave-siren to prove by 

 direct experiment the influence which phase has upon the 

 quality of a sound. The view taken by Koenig that this 

 difference may be completely explained by observing the 

 difference in the form of the resultant waves was also 

 briefly set forth. Two large diagrams were given which 

 illustrated the matter very completely. A set of odd 

 members only was taken from a harmonic series in which 

 the amplitudes decreased in inverse ratio to the order of 

 the harmonic ; the series having for the ratios of its fre- 

 quencies the numbers 1:3:5:7:9, with the respective 

 amplitudes 1 : \ : \ : 1 : J. These were compounded 

 together, firstly without any difference of phase, and 

 secondly with a difference of phase of £ the wave-length. 

 The resultant in one case showed well-rounded sinuosi- 

 ties, and in the other angular zigzags. In the first case 

 the whole of the components had at their origin zero 

 amplitudes, in the second they all, at the origin, had their 

 individual amplitudes at maximum values. Koenig found 

 the result, when the curves were actually tried upon his 

 wave-siren, to be that though the constituent tones in the 

 two cases were identical in pitch and amplitude the 

 resultant sound from the zig-zag curve was harsh and 

 strident compared with that produced by the rounded 

 sinuosities ; thus clearly proving an influence due to 

 difference of phase only. 



We give in Fig. 4 the resultant curves found by Koenig 

 in four typical instances. The first line of curves (a) 

 shows the resultants of a set of ten partial tones with 

 regularly diminishing amplitudes, as compounded to- 

 gether, first with no difference of phase, then with differ- 

 ences of j, i,and| respectively. The sounds corresponding 

 to these combinations were found to be loudest and most 

 forcible for difference of phase =|, and to be least 

 forcible for </= f , the phases of o and i having intermediate 

 intensity. 



Fig. 4 (6) illustrates the combination first mentioned 

 above, for which the differences of phase \ and i produced 

 a strident tone as compared with o and i, which agreed 

 in giving a smoother resultant sound. 



In Fig. 4 (c), which represents a series of harmonic 

 tones with amplitudes whose successive values diminish 

 each time by |, the results agreed in general with those 

 obtained from the same series when the amplitudes dimi- 

 nished less suddenly, the phases £ and i corresponding 

 respectively to the maximum and minimum of intensity. 



In Fig. 4(d), where again we deal with a series of odd 

 harmonics only, there is a harsher and louder sound for 

 d=\ and d=% than for d-o and d=^. 



In order to carry out these researches more fully, 

 Koenig has constructed a very large and complete appa- 



1 C.ntiiutd (Km p. 206. 



