June 19, 1885.] 



SCIENCE. 



497 



and Pterophyllums ; the monocotyledons through 

 their Aethophyllums and Ynccites ; and the 

 Coniferae through their Albertias, Walchias, 

 and Yoltzias ; while the less modified ancestral 

 type, which began even in the Permian to as- 

 sume a distinct Salisburian aspect in the genus 

 Ginkgophyllum, has come down to us, as 

 already described, through the several succes- 

 sive modifications which culminated early in 

 the tertiary in the modern form. This general 

 form was somewhat varied, widely distributed, 

 and quite abundant in miocene time ; but it is 

 now reduced to a single species, which was 

 probably restricted to the warmer or more 

 eastern districts of the Chinese empire before 

 it was transferred by human agency, and ac- 

 climated in Japan, to which country it is now 

 popularly credited. But it is said that there 

 is now no part of the world in which it is 

 found in a strictly wild state, being confined, 

 even in China, to the near vicinity of temples 

 and human habitations. 



This interesting tree has for many years been 

 cultivated on the continent of Europe, where it 

 thrives as far north as Copenhagen, but only 

 fruits freely in the more southern districts, 

 notably in the botanic garden at Montpellier, 

 France, where it has been exhaustively studied 

 by Professor Charles Martins and the Marquis 

 Saporta. In the United States there are now 

 many fine trees ; but they rarely flower, and, 

 when the}' do so, the sexes are seldom together, 

 so that fruit cannot be produced. The only ex- 

 ception to this known to me, or to any of whom 

 I have inquired, is the case of a pair of these 

 trees in the grounds adjacent to the University 

 of Kentucky at Frankfort, which are in such 

 close proximity to each other that fertilization 

 regularly takes place, and fruit is borne. 



It is owing to these circumstances that such 

 special interest attaches to the coincident 

 flowering this season, for the first time, of the 

 pair of maiden-hair trees in the botanic garden 

 at Washington ; and the rare opportunity, should 

 it be afforded, of witnessing all the steps in 

 the reproductive process of this historic type 

 of vegetable life, will be appreciated by both 

 botanists and vegetable paleontologists. 



Lester F. Ward. 



THE NEW CROTON AQUEDUCT. 



The necessity for an addition to the present 

 supply of water of New York has been felt 

 for many years, and the present Croton aque- 

 duct, finished in 1842, has become entirely 

 inadequate to meet the present requirements 



of the city. Never was the need of an addi- 

 tional supply better illustrated than in 1880, 

 when the authorities in charge stated, at the 

 end of a prolonged drought, that there was 

 only fifteen days' supply at hand. Timely 

 rains occurred shortly afterwards, and replen- 

 ished the water-sources. 



Since 1875, when two projects were pre- 

 sented for an additional water-supply, numer- 

 ous surveys were made, extending in several 

 instances beyond the limits of the present 

 collecting-grounds ; and in the beginning ot 

 1883 a committee of citizens, appointed by 

 the mayor at the request of the senate, pre- 

 sented to the legislature a report recommend- 

 ing that provision be made for the ultimate 

 storage of all the water from the Croton basin, 

 and for the immediate construction of a new 

 aqueduct. 



This sche^me is now being carried out by a 

 commission created by the legislature (Ma}', 

 1883), and composed of the mayor, comptrol- 

 ler, and commissioner of public works, and of 

 three citizens at large. 



The available watershed of Croton River 

 covers now 338.82 square miles. Its waters 

 are at present collected in several storage- 

 reservoirs, the lowest of which (Croton Lake) 

 acts also as a settling-basin, from which the 

 present aqueduct starts, and extends as far as 

 the main distributing reservoir in Central Park. 

 Owing to the limited capacity of the present 

 storage-reservoirs and of the aqueduct, a very 

 large proportion of the flow of the river is 

 unavoidably wasted over Croton dam. 



The present scheme consists in building 

 reservoirs capacious enough to impound the 

 copious spring flows, and in constructing a 

 larger aqueduct, through which the necessary 

 allowance of water can be drawn all the year 

 round from the new reservoirs. It is conse- 

 quently, in a general way, on a larger scale, a 

 duplicate of the present system ; but the very 

 scale on which the work is to be built gives 

 rise (as may be understood from the short 

 description which follows) to many interesting 

 and difficult engineering problems. 



It is estimated, that, in the dryest years, the 

 Croton watershed can furnish a daily supply 

 of 250,000,000 gallons, equivalent to"l00 gal- 

 lons per head per day for a population of two 

 million and a half souls, or to 75 gallons per 

 head for a population of three and one-third 

 millions. 



In order to store the large amount of water 

 necessary to provide this large daily supply 

 during the dryer months, it has been found 

 advisable to provide, at first, one reservoir of 



