386 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



time does not injure the levee, but leaves it so that it can be mowed 

 and kept clear of noxious weeds. Protections placed directly against 

 the slope form a refuge for muskrats and other pests that destroy 

 the levee. If made of creosoted lumber, it will not be attacked by 

 toredo and will last a great many years. The surface of the embank- 

 ment should be kept in grass and be carefidly mowed at least twice 

 each year. This will destroy the refuge for burrowing animals; 

 improve the sod, and become a source of revenue. 



TIDE GATES. 



When embanking a piece of marsh, provision must be made for 

 discharging the water that accumulates witliin the embankment. 

 Where the land is sufficiently above low tide, this can be most easily 

 accomplished by means of a sluice or tide gate. This provision for 

 the escape of the water is an essential feature of the reclamation, and, 

 like the embankment, must be properly designed and well built. 

 The ultimate success to be achieved in reclaiming salt marsh and 

 rendering it fit for meadow or cultivation depends almost wholly on 

 the character and efficiency of the tide gates devised and erected to 

 keep out the salt water. They must be of a permanent character, 

 substantially built, and so constructed as to open and close promptly 

 with a minimum amount of pressure. Care should be taken in plac- 

 ing the abutments that carry the gate to see that they have a firm 

 foundation and that the flow line of the chamber is slightly above 

 mean low tide. \Miat is known as the tankard gate, suspended by 

 a double hinge so as to readily close against the face on all sides, is 

 recommended. The seat is lined with rubber so as to form a tight 

 joint with the abutment, and if carefidly constructed will not allow 

 any water to pass when closed. As the gate is necessarily heavy, 

 an adjustable counterweight is attached so that it may Ix' nicely 

 balanced in order to open with a small head against the upi)cr side. 

 The position in which it is hung will cause it to close by gravity as 

 soon as the pressure on the inside is exhausted or overcome by an 

 equal pressure on the other side. In dosigiiiug the gates to accom- 

 modate a large volume of water, it is deemed better practice to make 

 a series of smaller ones having the required opening, as they can be 

 much lighter and are less liable to warp and spring, causing leaks 

 when closed. The relative merits of steel and wooden gates have been 

 considered, but owing to the difficulty in building and liolding struc- 

 tural work in a true plane and the deleterious effects of sail water 

 on steel and iron, it is thought that gates of creosoted timber are 

 better suited for the purpose. Th(> treatment of any porous wood, 

 preferably white or yellow i)ine, free from heart, with 14 j)ounds oi 

 creosote oil per cubic foot, will insure the material against tlecay, 

 prevent it from swelling and shrinking, and protect it against the 



