July 17, 1884] 



NA TORE 



271 



tion." We are told that "the various gases which con- 

 stitute ordinary coal-gas do not all burn together in the 

 flame ; . . . thus hydrogen is the first to burn, taking fire 

 readily as soon as it issues from the burner, while the 

 combustion of heavy hydrocarbons does not commence 

 until they enter the hotter portions of the flame." Again 

 Owen Merriman says: "the amount of light developed 

 by any coal-gas flame is directly proportional to the 

 degree of intensity to which the temperature of the carbon 

 particles is raised." The italics are ours. In a note 

 on page 23 there is some confusion as to the effect 

 of the admission of air into a Bunsen burner. " A 

 continuous wind blowing upon the flame destroys its 

 luminosity altogether, because the heat intensity of the 

 flame is lowered below the temperature necessary to de- 

 compose the hydrocarbons ; consequently these latter burn 

 without the preliminary separation of carbon, and a non- 

 luminous flame is produced — exactly as in the Bunsen 

 burner." The reader would gather from this that the 

 flame of a Bunsen was colder than an ordinary flame, and 

 by the same argument the blast of a blow-pipe would 

 render a gas-flame colder instead of hotter. And again 

 on page 43 a similar mistake is made when we are told 

 that a too long flame is bad because the gas is " brought 

 too early into intimate contact with air, and so oxidised, 

 or fully consumed, before its carbon has been raised to /In 

 temperature necessary to enable it to give out light." We 

 point out these few blemishes in the hope that the author 

 may correct them in a future edition of the work, to which 

 we wish a hearty success. 



BIRDS'-NEST SOUP 

 T T is scarcely probable that the famous birds'-nest soup 

 -l which Chinese cooks at the Health Exhibition offer 

 to favoured visitors will ever become a popular dish in 

 England. The tasteless, gelatinous compound is not 

 suited to our palates. Perhaps this is not to be regretted, 

 as the supply of material for this mysterious compound is 

 far from being inexhaustible. There appears to be only one 

 place in the world where it can be obtained in any quan- 

 tity, and this ha; recently been visited by Mr. Pryer, a 

 naturalist of Yokohama, who communicates his observa- 

 tions to the Japan Gazette, an English journal published 

 in that settlement. Leaving Elopura, the infant capital of 

 the infant colony of British North Borneo, in March last, 

 Mr. Pryer ascended for some thirty miles the Sapugaya 

 River, which flows into Sandakan Bay, on which the town 

 is built. Passing through the mangrove and nipa swamps 

 which line the banks, he arrived at noon on the second 

 day at his destination — the celebrated birds'-nest caves 

 of Gomanton. These caves, which are two in number, 

 called by the natives the Black and the White Caves, are 

 situated in a limestone cliff 900 feet in height, which the 

 traveller came on quite suddenly in the centre of the 

 forest. The porch, Mr. Pryer writes, is rather over 100 

 feet wide by 250 high, and the roof slopes up for no feet 

 more, so that the height of this magnificent natural cathe- 

 dral is 360 feet. The interior of the Black Cave is well 

 lighted, as there is a large circular hole in the roof 

 on the right, and a smaller one on the left, forming 

 two aisles. The walls and roof are rugged, and beauti- 

 fully coloured, shading from black to brown, gray, 

 dark yellow, red, and green. The nests of the bats 

 and swifts were seen hanging in clusters from the 

 sides and roof, and here and there in seemingly the most 

 inaccessible places were the rattan stages, ladders, and 

 ropes of the nest-gatherers. These latter reached their 

 perilous heights by means of many smaller caves in the 

 cliff above. The White Cave is 400 feet higher up than 

 the Black Cave, and at the entrance to this the nest- 

 gatherers live under a guard of the North Borneo Com- 

 pany's soldiers. After some examination Mr. Pryer was 

 able to discover the material which forms these mysterious 



nests, and from which they derive the qualities which 

 render them so highly prized in China. They are made 

 from a soft fungoid growth that incrusts the limestone in 

 all damp situations ; it grows about an inch thick, outside 

 dark brown, but inside white. The birds make the black 

 nests from the outside layer, and the best quality of white 

 nests are, of course, from the inside. It is taken by the 

 bird in its mouth, and drawn out in a filament backwards 

 and forwards like a caterpillar weaving its cocoon. At 

 nightfall takes place what the natives style with much 

 justice the most wonderful sight in all Borneo, and it 

 might be added, one of the most wonderful sights in the 

 world — viz. the return of the swifts to their nets, and the 

 departure of the bats for the night. About that time a 

 rushing sound was heard, and peering over the abyss into 

 the Black Cave Mr. Pryer saw columns of bats wheeling 

 round and round the sides in regular order ; soon they 

 began to circle up, rising into the air in a corkscrew flight. 

 Having reached a certain height, a detachment would 

 break off and fly away rapidly. He counted nineteen 

 flocks go off like this, each flock consisting of many 

 thousands, and then they commenced to pour away 

 in a continuous stream until it was too dark to see them 

 any longer. Soon after the bats emerged from their cave, 

 the swifts began to return to theirs, first in tens, then in 

 hundreds, and at last they too streamed in continuously, 

 and when the traveller went to sleep at midnight they 

 were still flying in in undiminished numbers. Rising be- 

 fore daylight the following morning, Mr. Pryer witnessed 

 a reversal of the proceedings of the previous night, the 

 swifts going out and the bats coming home. The latter, 

 he says, literally rained into their chasm for two hours 

 after sunrise ; looking up to the bright sky, numbers ot 

 small specks appear, flash down perpendicularly with 

 great rapidity, and disappear into the darkness. From 

 specimens of the bat which were secured, they were found 

 to be all of one species, the caudal membrane extending 

 only half down the tail, which is free for an inch and a 

 half, giving the animal, when the wings are folded up, 

 very much the appearance of a mouse. The wings are 

 very long and narrow, and it flies with great speed. Two 

 species of birds of prey — one a kite, the other a hawk — 

 the Haliaster Indus and the Maclueramphns alcinus, prey 

 on the bats and swifts when swarming into and out of the 

 caves. A detailed examination of the latter was rendered 

 disagreeable by enormous quantities of guano, the deposit 

 of centuries. Its depth is not known, but a long spear 

 does not touch the bottom when thrust in to the hilt. All 

 the roof of the dark parts of the cave was occupied by- 

 birds who keep up an intermittent twittering, sounding, 

 from the immense number of them, like the surf beating 

 on a rocky shore. Near the centre of the largest cave 

 the explorer was shown a small beam of light from ■ 

 a funnel at the top of the rock, exactly 696 feet above 

 his head. The nests are gathered from these enor- 

 mous elevations by means of flexible rattan ladders and 

 stages. On these two men take their station ; one carries 

 a light four-pronged spear about 1 5 feet long, and just 

 below the prongs a lighted candle is fixed. Holding on 

 to the ladder with one hand, the spear is managed with 

 the other, and the nest transfixed, a slight push detaching 

 it from the rock. The spear is then withdrawn until the 

 head is within reach of the second man, who takes the 

 nest off the prongs and puts it in a pouch carried at the 

 waist. According to statements made by the headman 

 of the place, the annual value of the nests taken varies 

 from five to six thousand pounds sterling. This, it is to 

 be presumed, means the value on the spot ; their value 

 on reaching China must be far higher. The caves have 

 been worked for seven generations without any apparent 

 diminution, although three crops are gathered in the year. 

 Notwithstanding the dangerous nature of their occupation 

 — for even samphire-gatherers work in the open — acci- 

 dents are very rare amongst the natives employed in 



