TYPICAL MASONRY AND EARTHWORK DAMS OF THE WORLD.
The accompanying table gives the pressures to which various dams are subjected, and it may be noted with regard to the weight of water, generally assumed as 62.4 lb. per cubic foot, that it will, in some districts, in time of flood, carry so much matter in suspension as to be increased to as much as 75 lb. weight, or an addition of 20 per cent., which, it may be easily imagined, will affect the conditions of stability very seriously.
| TABLE OF MAXIMUM PRESSURES. | |
| Lb. per sq. in. | |
| Gileppe (Verviers). | 88 |
| Furens (St. Etienne). | 93 |
| Puentes. | 112 |
| De Ban. | 113 |
| St. Chamond. | 114 |
| Alicante. | 154 |
| Hamiz (Algeria)—failed. | 157 |
| Habra (Algeria)—failed. | 185 |
A diagram comparing the section derived from Molesworth's formula and those of Furens, Gileppe, Vyrnwy, and Quaker Bridge, is given at Fig. 20, the limit of pressure assumed for the masonry being 93 lb. per square inch, which is that of the Furens, the Gileppe being 88.
NEW DREDGING MACHINERY.
We illustrate the new dredger Ajax, recently built for Mr. Geo. F. Smith, of Stockton, Cal.
The dredger has now been working for two weeks at Wakefield, and, we are informed, is giving entire satisfaction; having been repeatedly timed to be discharging clay at the rate of 220 cubic yards per hour.