574 



THE POPULAR SCIENCE MONTHLY. 



it were perpetrated in the name of public 

 utility. Even the French for once agreed 

 with the English about what should be done 

 in Egypt. The plan was changed. The ma- 

 jestic structure of the dam will be cut down 

 thirty-seven feet, so as to be only eighty-eight 

 feet high, and Philas will stand in a lake, but 

 will not be drowned. 



Patiuas of Japanese Bronzes. Describ- 

 ing the patinas of Japanese bronzes, Mr. 

 W. Gowland, late of the Imperial Mint, says 

 that in many bronzes the beautiful color is 

 due to a " stain " or colored film of infini- 

 tesimal thinness. In others, the surface of 

 the metal is altered to a considerable depth, 

 and in these only we have true patinas. Fre- 

 quently both a stain and a patina are pro- 

 duced by similar treatment, but the opera- 

 tions required for the latter are of a more 

 prolonged character than for the former, and 

 are accompanied by special manipulations in 

 addition to the application of what are called 

 pickling solutions. For the production of 

 patinas of the richest and darkest shades of 

 brown by Japanese methods, it is essential 

 that lead should form one of the constituents 

 of the bronze, and that zinc should either be 

 absent altogether or be present only in small 

 proportions. On the other hand, stains of 

 any color can be given to metal of any com- 

 position, and even to unalloyed copper. The 

 substances used in the operations are cop- 

 per sulphate, basic acetates of copper (verdi- 

 gris), iron sulphate, sulphur in fine powder, 

 alum, vinegar prepared from unripe plums, 

 and a decoction of the roots or entire plant 

 of Calamagrestis Hakcnensis (natural order 

 Graminece), potassium nitrate, and sodium 

 chloride. The most important of these re- 

 agents are the first five. The processes for 

 producing a patina by the use of the various 

 solutions of these substances are somewhat 

 complicated and difficult, and the interme- 

 diate operations, on which its production de- 

 pends more than on the exact composition of 

 the solution, are variously modified in differ- 

 ent foundries. 



The Peril of Color-Blindness. Renewed 

 attention has been called by Surgeon W. M. 

 Beaumont, of the Bath (England) Eye In- 

 firmary, to the importance of perfect color 

 vision for railway servants, which is unques- 



tioned in the minds of ophthalmic surgeons, 

 however other doctors and railway directors 

 may be disposed to ignore it. Some ques- 

 tions asked by one of the doubting doctors, 

 whether, since attention has been turned to 

 the subject, any accident has been brought 

 home to defect in color vision, or other facts 

 demonstrating the theory have been brought 

 out in usual practical sailing and railway 

 life, are answered by reference to several 

 illustrative incidents that have been gath- 

 ered. Of these are the wreck of the steamer 

 City of Austin, on the Florida coast, with a 

 color-blind pilot ; the collision of the Corbet 

 Castle and the T. H. Ramieu, due to the 

 color-blindness or short-sightedness of the 

 chief officer ; the collision of the Lumber- 

 man and the Isaac Bell, near Norfolk, Va., 

 the Lumberman's master being color-blind, 

 and consequently taking the wrong course 

 with his vessel ; and the narrow escape of 

 the steamer Neera from a collision through 

 the color-blindness of its officer. In an- 

 other instance the color-blindness of a rail- 

 way fireman and the imminent danger of 

 collision thereby were experimentally deter- 

 mined in the ordinary working of the train. 

 Even where the color-blind engineer believes 

 he can distinguish between the signals, and 

 appears to do so, he does it, not by the color, 

 but by the difference in intensity. This is 

 a very uncertain and indefinite factor, and 

 is liable to variations according to the 

 weather, the condition of the engineer, and 

 other causes not so well known, and can not 

 be safely depended upon. 



Farming on the Yang-tse Kiang. The 



country in China along the Yang-tse River 

 from Shanghai to Hankow, and for a hun- 

 dred miles on either side of the river, is, in 

 general, a rich alluvial plain, traversed by 

 ranges of hills having an east and west trend. 

 The tops of the hills give the best tea, and 

 where the ground is stony fir and oil trees 

 are planted, for oil, resin, timber, and fire- 

 wood. On lands of intermediate height or 

 where the land is not suitable for rice cot- 

 ton, wheat, corn, buckwheat, sweet potatoes, 

 and kitchen vegetables are grown in great 

 profusion. Dairy farming is unknown, and 

 milk is looked upon with disgust. The na- 

 tive buffalo is the domestic animal employed 

 in cultivating rice. Three crops can geuer- 



