FRAGMENTS OF SCIENCE. 



733 



could be bought for twenty-five cents 

 an acre in large tracts, but it now brings 

 from two dollars to five dollars Mexican. 

 These lands can be used for other crops 

 while the trees are growing up, and thus 

 made partly to repay the cost of start- 

 ing the plantation. So the expense of 

 clearing the land preparatory to plant- 

 ing it is largely met, if facilities for 

 transplantation are at hand, by the sale 

 of the dyewoods, sandalwood, satin- 

 wood, ebony, and mahogany that are 

 cut ofi". The land should be chosen 

 along the banks of streams, wheie the 

 soil is rich, deep, and loamy, and the 

 presence of wild rubber trees is a sure 

 indication of its suitability. These wild 

 trees should be left standing, and young 

 seedlings should be kept and trans- 

 planted into their proper places. The 

 densest plantation compatible with good 

 results is fifteen feet apart, giving about 

 one hundred and ninety-three trees to 

 the acre. Once in the ground, the tree 

 needs no attention or cultivation be- 

 yond keeping down the undergrowth, 

 which can be eiTeeted by the aid of a 

 side crop. The tree propagates itself by 

 the seeds or nuts, which drop in May 

 and June. By the sixth or seventh year 

 the grove will be in bearing, and there- 

 after should yield from three to five 

 pounds of India rubber per tree. 



The New York Botanical Gar- 

 den's Museum. — The museum buildinp 

 of the New York Botanical Garden is 

 substantially completed, and most of 

 the works are in an advanced state of 

 forwardness. The museum cases (for 

 public inspection) and the herbarium 

 cases (for students) are in position, and 

 the herbarium cases are filled. Among 

 the recent gifts of value to the institu- 

 tion are the miscellaneous collection of 

 John J. Crooke, made about thirty 

 years ago and containing about twenty 

 'thousand specimens, among which are a 

 set of the plants obtained by the United 

 States Pacific Exploring Expedition of 

 about 1850; the collection of between 

 twenty and thirty thousand specimens 

 made by Ur. F. M. Hexamer in Switzer- 

 land and the United States; a collec- 

 tion of seven or eight thousand num- 

 bers, made by Mr. and ]\Irs. A. A. Hel- 

 ler, representing between twelve and 

 thirteen hixndred species, some of which 

 are new to science; and specimens of 



crude drugs, for the Economic Museum, 

 presented by Parke, Davis & Co. A 

 permanent microscopic exhibition is to 

 be established by Mr. William E. Dodge, 

 at his own expense. It will be fur- 

 nished with at least twenty-five micro- 

 scopes, and with specimens carefully 

 prepared and inclosed, to secure them 

 from injury. A set of more than two 

 hundred volumes on botany and horti- 

 culture, which formed a part of the 

 library of Dr. David Hosack, founder of 

 the first botanical garden in New York, 

 has been presented by the New York 

 Academy of ^ledicine, which received it 

 from the New York Hospital. 



Action of Sea "Water on Cements. 

 — As the result of examinations of many 

 masonry structures immersed in sea 

 water. Dr. Wilhelm Michaelis has found 

 that Portland cement does not resist the 

 chemical action of such water so well as 

 do Eoman cement and the hydraulic ce- 

 ments. The soluble sulphates in the sea 

 water appear to enter into a subsLitution 

 combination with the lime which exists 

 in the cement in a free state or is liber- 

 ated in the hardening, and it is con- 

 verted into a sulphate, while disintegra- 

 tion ensues. In Roman cement the lime 

 exists in combination, and there is no 

 inclination toward the formation of a 

 sulphate, and hydraulic limes resemble 

 Roman cement in physical qualities. 

 Dr. Michaelis suggests that hydraulic 

 cementing materials containing more 

 lime than is required for the formation 

 of stable hydro-silicate and aluminate 

 may be made suitable for submarine 

 work by an admixture of trass or puzzo- 

 lana, whereby the cementing strength 

 of the mass will be greatly increased, 

 and it will be enabled to withstand the 

 disintegrating action of the sea water.. 



Stories of Amazonian Pygmies. 

 — Dr. D. G. Brinton subjected the stories 

 of the existence of pygmy tribes on the 

 upper tributaries of the Amazon to a 

 careful examination, and came to the 

 conclusion that the facts did not show 

 anything more than that there are un- 

 dersized tribes in that part of South 

 America, with occasional individual ex- 

 aniples of dwarfs, such as occur in all 

 communities. It is still a question, he 

 observed, " whether the rumor of a pyg- 

 my people somewhere in the tropical for- 



