166 History of Mechanical Inventions and 



age and country as a standard of irutal and untameable fury. India ex- 

 hibits numerous proofs of false conclusions by natural historians regarding 

 the habits and temper of animals, and affords a field of interesting inquiry 

 respecting their instinct, as contradistinguished to what might be called 

 their educatable faculties. — This subject has hitherto, we believe, only been 

 treated by the naturalists of Europe, who have relied in many cases upot> 

 very vague or insufficient narratives, but never by any person residing 

 in the native country of the animals whose history has been recorded. 



7. On the Edible Birds' Nests of the Tavoy and Mergui Islands in Siam, 



Edible birds' nests are found in considerable quantity on the islands off 

 the Tavoy coast, but they are very generally met with throughout the 

 Archipelago. They are in most perfection m January, but are gathered 

 also during the six weeks preceding and following that month. The quan- 

 tity obtainable in any one season is uncertain, for Malay, Chinese, Siamese,, 

 and other boats are accustomed to come in amongst the islands, and to 

 carry off part of the produce : it also partly depends upon the dexterity of 

 the nester, who, by disturbing the swallows just when the nest is com- 

 pleted, obliges them to multiply their labours. The operation of the 

 nester is not always free from danger, as he has to climb precipices by the 

 help of ropes and flying ladders made of rattans, and the caves into which 

 he has to penetrate are noisome, and in some places so intricate, that he is 

 apt to lose himself. — The nesters use considerable quantities of arrack and 

 opium. It is probable that the Burman collections did not exceed two 

 Peculs in the season, but there is little doubt that five or six times that 

 quantity might be obtained. 



The farm of these nests, which had let the year before only for 50O 

 rupees, was knocked down since we took possession, at 15,000 rupees for 

 those of the Tavoy Islands alone ; and 3000 rupees more were expected for 

 those of the Mergui Islands, 



Art. XXXVI.— HISTORY OF MECHANICAL INVENTIONS 

 AND PROCESSES IN THE USEFUL ARTS. 



1. On the Explosion of Steam Boilers. * By Jacob Perkins, Esq. 



It has been generally considered a well established fact, that the caloric 

 of steam, at a given elasticity, is invariably the same when in contact 

 with water ; but this is far from being the case. It may be, and often is, 

 £0 generated as to indicate very high degrees of temperature without a cor- 

 responding increase of power, so as evidently to prove that temperature 

 alone cannot be relied on as a measure of the elastic power of steam. Ma- 

 ny experimentalists have thus undoubtedly been led into error, especially 



• Mr Perkins has been so obliging as to transmit to us copies of this and the fol- 

 lowing article, which he has printed for the information of his scientific friends — 

 Ej>. 



