April 9, 1886.] 



SCIEXCE. 



333 



the greater importance in connection with then- 

 relative merits as lighthouse illuminants. 



The final conclusion of the experimenters was, 

 that, for the ordinary necessities of lighthouse 

 illumination, mineral oil is the most suitable and 

 economical illirminant, and that for salient head- 

 lands, important land-falls, and places where a 

 very powerful light is required, electricity offers 

 the greatest advantages. 



METAL- WORK OF THE BURMESE. 



Both Burmans and Shans are expert black- 

 smiths, says the Journal of the Society of 

 arts. The latter forge all the dahs ( ' native 

 hatchets') used by themselves and their neigh- 

 bors in the Hotha valley ; and they annually re- 

 sort to Bhamo, and the villages in the Kakhyen 

 hills, for the purpose of manufacturing them. 

 Their bellows are of the most primitive stamp, 

 consisting of two segments of bamboo, about four 

 inches in diameter and five feet long, set verti- 

 cally, forming the cylinders, which are open above 

 and closed below, except by two small bamboo 

 tubes, which converge and meet at the fire. Each 

 piston consists of a bunch of feathers, or other 

 soft substance, which expands and fits tightly in 

 the cylinder while it is being forcibly driven down, 

 and collapses to let the air pass as it is being 

 drawn up. A boy perched on a high seat or 

 stand, works the two pistons alternately, by the 

 sticks serving as piston-rods. Charcoal is used for 

 fuel. 



The casting of large and small articles in brass, 

 bronze, and other alloys, is much practised, always 

 adopting the method known as a cire perdue. 

 First a clay model is made, and coated with bees- 

 wax to the thickness of the intended cast, and 

 again covered with an outer skin (two inches 

 thick) of clay mixed with finely chopped straw ; 

 this latter coat is provided with funnel-like holes, 

 for pouring in the molten metal, at intervals of 

 four inches, and with straw-holes for letting out 

 imprisoned ah*. Holes are also provided at the 

 bottom for the escape of the melted wax. 



THE GREAT SILVER-MIXES OF THE 

 WEST. 



Valuable indeed have been the scientific re- 

 sults which geology has incidentally received 

 through the great mining undertakings of the 

 west. The studies of von Richthofen, of King, 

 and of Zirkel, on the rocks of the Washoe, have 

 been equally welcome to geologists at home and 

 abroad as contributions to the general principles 

 of their science. 



The importance of a thorough and detailed 

 geological investigation of regions possessed of 

 great mineral wealth is at once apparent. The 

 geologist may afford the prospector and the capi- 

 talist just that information which is most needed ; 

 while, in turn, the shafts and tunnels of the latter 

 supply him with sections and exposures of the 

 rocks, which he could never otherwise hope for. 

 How keenly the advantages of such a combina- 

 tion are appreciated by the government geological 

 survey is abundantly proven by the recent elabo- 

 rate monographs by Becker on the geology of the 

 Comstock Lode, and by Irving on the copper- 

 bearing rocks of Lake Superior ; while others of 

 a similar nature are now in course of preparation 

 on the silver districts of Eureka and Leadville by 

 Messrs. Hague and Emmons. Nor may we pass 

 without mention, in this connection, the extreme- 

 ly important contribution recently made by 

 Messrs. Hague and Iddings to what we know of 

 the influence of heat and pressure in conditioning 

 the structure of an eruptive rock. No such con- 

 clusive evidence that the holocrystalline struc- 

 ture of an igneous mass depends upon the slow- 

 ness with which it solidifies, had ever before been 

 discovered as that which they found in the micro- 

 scopic study of the rocks displayed in the hundred 

 and eighty miles of shafts and galleries at the 

 Comstock. 1 



But the value of such technical papers can at 

 most be appreciated only by a few. Specialists 

 in the same field of scientific inquiry, or the pros- 

 pector or miner who consults them in hope of 

 some practical suggestion, will be their only read- 

 ers, even though the results which they contain 

 are broad and far-reaching in then- significance. 



Nevertheless there is connected with the de- 

 velopment of a vast mining industry very much 

 to awaken a popular interest. The accidental dis- 

 covery of rich mineral treasures in the heart of a 

 mountain wilderness ; the rushing thither in 

 hordes of men of every type, all eager to secure 

 the largest prize ; the human ingenuity and energy 

 displayed in overcoming the vast obstacles which 

 nature has placed in the way of transportation ; 

 the story of successes and disappointments, of 

 fortunes made and lost, — all this gives scope for 

 the display of the strongest human passions, 

 and contains the elements of a tale whose truth is 

 more romantic and more exciting than fiction. 



In a volume 9 quite different in its character 



1 Bulletin No. 17 of the U. S. geological survey. On the 

 development of crystallization in the igneous rocks of 

 Washoe, Nevada. 



2 Monographs of the V. S. geological survey. Vol. iv. 

 Comstock mining and miners, by Eliot Lord ; vol. vii. 

 Silver-lead deposits of Eureka, by J. S. CrRTis. Washing- 

 ton, 1833, 18S4. 4°. 



