The average results of the complete analyses of sands from ten leading works are shown in the table on page 28. These figures are the average of all the analyses for the respective places, except that one sample from the Lambeth Co., which was not a representative one, was omitted. The London companies were selected for this comparison both on account of their long and favorable records in filtering the polluted waters of the Thames and Lea, and because they are subject to close inspection; and there is ample evidence that the filtration obtained is good—evidence which is often lacking in the smaller and less closely watched works. For the German works Altona was selected because of its escape from cholera in 1892, due to the efficient action of its filters, and Stralau because of its long and favorable record when filtering the much-polluted Spree water. These two works also have perhaps contributed more to the modern theories of filtration than all the other works in existence. The remaining works are included because they are comparatively new, and have been constructed with the greatest care and attention to details throughout, and the results obtained are most carefully recorded. Some of the most interesting of these results are shown graphically on page 29. The method of plotting is that described in Appendix III. TABLE SHOWING THE AVERAGE PER CENT OF THE GRAINS FINER THAN VARIOUS SIZES IN SANDS FROM LEADING WORKS. --------------+---------------------------------------------------- | Per Cent by Weight Finer than +------+------+------+-----+-----+-----+-----+------- |0.106 |0.186 |0.316 |0.46 |0.93 |2.04 |3.89 |5.89 | mm. | mm. | mm. | mm. | mm. | mm. | mm. | mm. --------------+------+------+------+-----+-----+-----+-----+------- East London | 0.2 | 0.5 | 3.6 |22.2 |69.7 |89.8 |95.0 |99.0 Grand Junction| 0 | 0.2 | 3.1 |17.4 |47.1 |68.2 |84.7 |93.6 Southwark and | | | | | | | | Vauxhall | | 0.7 | 8.0 |34.1 |69.7 |83.5 |90.0 |94.0 Lambeth | 0 | 0.5 | 5.5 |26.6 |63.0 |79.2 |88.0 |94.3 Chelsea | 0 | 0.1 | 5.0 |28.6 |63.0 |76.7 |86.0 |93.6 Hamburg | 0.2 | 1.5 |10.9 |33.2 |74.4 |95.7 |99.5 | Altona | 0.1 | 1.1 | 7.8 |28.7 |72.1 |92.1 |95.8 | Stralau | | 0.3 | 7.0 |37.3 |86.9 |95.4 |97.6 | Tegel | | 0.2 | 4.5 |35.4 |94.3 |98.5 |99.1 | Müggel | 0.1 | 0.5 | 7.9 |33.6 |79.7 |94.3 |98.5 | +------+------+------+-----+-----+-----+-----+------- Average of all| 0.06 | 0.56 | 6.33 |29.71|71.99|87.34|93.42|(97.45) --------------+------+------+------+-----+-----+-----+-----+------- AVERAGE EFFECTIVE SIZE, UNIFORMITY COEFFICIENT, AND ALBUMINOID AMMONIA IN SANDS FROM TEN LEADING WORKS.