FRESH- WATER MUSSELS AND MUSSEL INDUSTRIES. 49 



String is to be substituted. The soft line wears better than any other kind, especially 

 where the bottom has much sand and gravel. Chains, or long wire links, are sometimes 

 used in place of the cotton twine, but, although they last much longer, they are not 

 often employed, owing to the extra weight and cost. Each line carries from two to six 

 hooks, attached at intervals of sufficient distance to prevent successive hooks from 

 interfering with one another. 



The bridle is a small-sized rope, about 0.5 inch in diameter, and is attached to the 

 bar near the ends. It is left loose, so that it may be tied to the main rope about 2 feet 

 above the middle of the bar. 



The main rope, or cable, is larger, being usually about 0.75 or i inch in diameter, 

 while its length varies according to the depth of water, generally from 25 to 35 feet 

 being required. The rope is tied to the middle of the bar and to the center of the bridle. 

 To obviate difficulty from twisting and to make the rope available when desired for 

 other purposes, the attachment to the bridle is usually made by a swivel snap and ring. 



The mule. — An essential feature of the outfit with this method of fishery, under 

 ordinary conditions, is the underwater sail or mule, as it is called. When the mussel 

 fisherman is ready for work and the boat is over the shell bed, the bar is thrown over- 

 board. The hooks of the bar catch in the river bottom, as well as in the shells, and thus, 

 acting as anchors, will stop the progress of the boat downstream, unless additional power 

 is supplied. In order to derive this power from the current, the mule is lowered into 

 the river at the stem of the boat, to which it is connected by guide lines. Its broad 

 surface is at right angles to the current, and the entire outfit is thus forced slowly down 

 the river, stern first, in spite of the drag on the bottom. By means of the guide lines 

 the mule is easily regulated to steer the boat at a desired angle over the mussel bed, or 

 to avoid a familiar snag. 



There are two well-know^n types of mules in use on the different rivers — the common 

 frame type and the roll mule. 



The frame type is rectangular in form, the outline or framework consisting of light 

 strips or narrow boards about 3 inches wide by 0.75 of an inch thick, sometimes with a 

 center strip extending from the middle of the bottom to a few inches above the top. In 

 Plate XXVII, figure i, a mule is shown lying on the stem of the boat; see also Plate 

 XXIX, figure i. The frame is covered with strong cloth, such as muslin, canvas, tar- 

 paulin, gunny sacking, etc., which is left rather baggy in order to make the appliance 

 more steady in the water; otherwise when the current strikes it at an angle it is liable 

 to turn over, dart forward, and "kick." This characteristic accounts for its technical 

 designation as "mule." It is connected to the boat by lines running from the four 

 comers, excepting for those patterns having the center strip, when three connections 

 are made with the lower corners and the top of the strip. 



The roll mule is not used so extensively as the frame type, but it is very popular 

 on the Illinois and some other rivers. It consists of a piece of canvas, tarpaulin, or 

 heavy cloth cut according to the size and shape desired. An iron rod is attached to the 

 bottom of the mule and a wooden bar at the top. To the four comers of the cloth small 

 lines are secured for the purpose of adjusting the mule to the boat. This form of mule 

 has the advantage over the other in that when not needed as a sail it can be rolled up 

 and put out of the way in the boat or used as a tent against unfavorable weather. It is 



