86o 



THE POPULAR SCIENCE MONTHLY. 



Chirambira Bay, and the higher waters of 

 the river Atrato, which flow into the Atlan- 

 tic through Choco Bay, in the Gulf of Da- 

 rien, so that they could pass from the Carib- 

 bean to the Pacific in their canoes. In 

 carrying this passage into effect, the Aras- 

 tradera, or summit level, a plain about three 

 miles in width, formed by an interruption of 

 the mountainous ridge, was cut across. The 

 passage was, however, dangerous and diffi- 

 cult at all times, even for canoes, and the 

 communication has now for many years been 

 neglected and disused. 



Land Tenures in China. While the em- 

 peror theoretically owns all the land in Chi- 

 na, the private owner has as absolute a 

 property in it as he can have under any gov- 

 ernment. The tenures are military and com- 

 mon, the latter applying to far the largest 

 proportion of the territory. , It exists upon 

 the conditions of payment of the land-tax, 

 the supply on demand of statute labor to the 

 authorities, and the payment of a fine on 

 alienation. The land-tax is assessed in a 

 fixed sum on the district magistrate, who 

 recovers from the tenant, but is sometimes 

 remitted in case of a great calamity. The 

 supplying of statute labor has almost fallen 

 into disuse. The fees are payable on the 

 transfer of land by sale or mortgage, suc- 

 cession or inheritance. About half the soil 

 is probably the property of the tenants who 

 till it ; but large tracts are also owned by 

 " literati and gentry," who lease it to small 

 farmers for a rental consisting of a propor- 

 tion of the crops fixed according to the qual- 

 ity of the soil. The rents are paid as soon 

 as the crop is harvested, and, being seldom 

 in arrear, evictions are rare. The laws are 

 all in favor of the tenant, who pays no taxes 

 or rates, and takes everything, including his 

 house. There is every possible variety of 

 arrangement in the ownership of land. There 

 are absolute sales and sales in which the 

 vendor reserves the right to a share in a 

 future rise in value ; revocable and irrevoca- 

 ble sales ; and dual ownership, in which one 

 man owns the surface and the other the 

 soil, and is liable for the taxes. 



Refrigeration by Ammonia. Ammonia 

 has been very generally employed for re- 

 frigerating purposes in the United States 

 and Germany, and to some extent elsewhere, 



for ten years or more. Other agents used 

 for this purpose are methylic ether, Pictet's 

 liquid, sulphur dioxide, and ether. Ammonia 

 in its anhydrous condition possesses in an 

 eminent degree the properties most desired 

 in a refrigerant, for it boils at the low tem- 

 perature of 374- Fahr., while its latent heat 

 of vaporization is 900. Two distinct sys- 

 tems are employed in the use of ammonia, 

 differing from one another in the method of 

 securing the rejection of heat during conden- 

 sation of the vapor, while the mere evapo- 

 rating or refrigerating part of the process is 

 the same in both. In the absorption process 

 ammonia and water are vaporized together 

 and then fractionally condensed by cooling. 

 The water, condensing first, is caught and 

 run back to the generator, while the nearly 

 anhydrous ammonia is collected separately. 

 With this process 200,000 units of heat per 

 hour may be eliminated by the consumption 

 of about one hundred pounds of coal, with 

 a temperature in the refrigerator of about 

 20 F. In the compression process the 

 ammonia vapor is drawn from the refriger- 

 ator and compressed by a pump and deliv- 

 ered into the condenser and liquefied at the 

 temperature of the cooling water. It is 

 more economical than the absorption pro- 

 cess, and is adequate to the elimination of 

 240,000 units per hour. The process is ap- 

 plied to ice-making and to the cooling of 

 stores and rooms. 



The Tahl-tan Indians of British Colum- 

 bia. An account of this people by Mr. J. C. 

 Callbreath, included in a report of an explo- 

 ration by George M. Dawson, gives their max- 

 imum height as about five feet seven and a 

 half inches, and maximum girth of chest 

 about thirty-seven inches. Their heads are 

 small, and the feet and hands are generally 

 small, as are also the wrist and ankle, espe- 

 cially in the women. Traders sell more No. 

 2 women's and No. 6 men's shoes than any 

 other sizes. No men's hats above No. 1 are 

 sold. Bialf-breeds from a white man and a 

 Tahl-tan woman are more like the father than 

 the mother, and three generations where the 

 father is in every case white seem to oblit- 

 erate all trace of Indian blood. The children 

 are more cunning and clever when young 

 than those of the white race, but grow dull 

 as they age. Yarn is spun from the wool of 



