216 ANNUAL OF SCIENTIFIC DISCOVERY. 



38 species of plants, contributing in a more or less degree to the 

 mown produce, of which about 75 per cent, was graminaceous, 6 per 

 cent, leguminous, and 19 per cent, miscellaneous. Mineral manures, 

 on the other hand, gave 37 species, and the produce contained only 68 

 per cent, of graminaceous and 9 per cent, of miscellaneous, but 23 per 

 cent, of leguminous herbage. Ammonia; salts gave 32 species ; 89 per 

 cent, of the produce being graminaceous, nearly 11 per cent, miscel- 

 laneous, and only 0.5 per cent, leguminous. When the mineral 

 manures and ammonia salts were employed together, in quantities 

 sufficient to yield large crops, only from 20 to 26 species could be 

 detected, and from 90 to 95 per cent, of the total produce was gram- 

 inaceous, there being scarcely a vestige of leguminous herbage then 

 to be found. The influence of ordinary farm-yard manure, of nitrates, 



* *' 



and other manuring substances, was also indicated. It happened that 

 large crops could only be obtained when large amounts of nitrogenous 

 as well as mineral constituents were employed; and, under these cir- 

 cumstances, the produce would be in very large proportion gramina- 

 ceous, while leguminous herbage almost entirely disappeared, as also 

 did numerous miscellaneous plants, though some few, as plantago, 

 rumex, ranunculus, milfoil and carum, were one or more increased in 

 quantity according to the description of the manure. In the experi- 

 ments in question the largest crops were not only almost wholly gram- 

 inaceous, but the great proportion consiste'd of but few genera, the 

 principal being dactylis, poa, holcus, lolium, and agrostis. In fact, it 

 seemed impossible to have at once large crops and great complexity 

 of herbage. This was a point of considerable interest just now in 

 connection with the question of the application of town sewage to 

 grass land, In some experiments on the application of sewage at 

 Bugby, it was found that the herbage became more simple, the bulk 

 of the produce consisting of dactylis, lolium, and holcus, with scarcely 

 any leguminous herbage, but a good deal of ranunculus, and more or 

 less of some other weeds and other grasses than the three named. 

 On a large proportion of the sewage meadows at Edinburgh, again, 

 the produce was composed almost exclusively of three or four species, 

 of which triticum repens and loiium perenne were the most predomi- 

 nant. 



SEWAGE AND HEALTH. 



In a paper recently read before the London Society of Arts, Mr. 

 Rawlinson, a distinguished English engineer, stated that the death- 

 rate of London and of the great manufacturing towns of England 

 diminished just in proportion to the abolition of sinks and cesspools, 

 and to the perfection and completeness of sewage drainage. The 

 author maintained that if all the sewers were of sectional dimensions, 

 forms, and gradients (as they might be), to transmit fresh sewage, and 

 not retain it until putrefaction sets in, the public health would be 

 further improved. The full and proper ventilation of sewers and 

 drains was of the utmost importance ; drains should be so laid and 

 arranged as to render contamination of the air within houses by 

 sewage gases impossible. Sewers should not pass beneath houses, 

 and drains should commence at external walls, so that neither sewer 

 nor drain should be beneath the basement of any house. 



