PEINCIPLES OF DESIGN. ^ i'69 



natives' hands. The practice has been and is now to a great 

 extent to fell the trees, making incisions in the form of rings in 

 the trunli, from which the gum oozes out and is collected, dried, 

 and while plastic rolled or shaped into separate pieces. The 

 process of felling is immensely destructive of forest supplies 

 and much to be deplored. But it is difficult to put a check on 

 this wanton practice where the collection is by natives, who 

 find the trees themselves in the interior of dense virgia forests. 

 In plantations where gutta trees are cultivated, the collection 

 is made yearly by incisions in the trunk without felling. 

 Attempts are being made to extract this valuable product from 

 the leaves only. Prof. Ramsay has tried treating the desiccated 

 leaves and stalks of young shoots of the tree by dissolving 

 them completely in a certain agent and then applying a 

 re-agent which precipitates gutta-percha in flakes. 



There are many different species of gatta trees, the yields of 

 which vary considerably in the qualities suitable for cable pur- 

 poses. The most valuable species is the "Isonandra Gutta," 

 which possesses more than any other kind the property of 

 undergoing no change as a dielectric for an almost indefinite 

 period under water. 



In a very instructive article on this subject in La Lumiere 

 Electrique, by M. SeruUas, in 1890 (reproduced in the Electrical 

 Bevieio, Vols. XXVII. and XXVIII. ), he gives the character- 

 istics by which this tree may be distinguished. It does not 

 propagate itself readily by seed, and only in its immediate 

 vicinity. The seeds, moreover, are sought after as food by 

 certain birds and animals, and it only thrives in certain con- 

 ditions of soil and climate. Adding to this the destruction of 

 trees wholesale in the past, it is no wonder that supplies from 

 this particular tree are running short. It was found first in 

 Singapore, Malacca, Selangore and Perak, and at one time 

 these districts were among the most fruitful in their yield. 

 But collection ceased owing to shortage of trees in 1884, and 

 the best supplies now come from Bjrneo, Sarawak and Java; 

 Mr. Wray's researches, carried out in 1882 and 1883, should 

 be mentioned. The Government of the Straits Settlements 

 commissioned thia gentleman to examine into the different 

 species of gutta trees, and the supplies available in the State of 

 Perak in the Malay States, and he performed most valuable 



