i86 



SCIENCE-GOSSIP. 



Construction of a Tow Net. — Mr. C. A. Kofoid 

 gives the following details in the " Illinois State 

 Laboratory Bulletin" on the construction of a 

 tow net which is inexpensive, durable, and so 

 constructed as to facilitate the removal of the 

 catch for preservation. The bag of the net may 

 be made of fine India muslin. In cutting out the 

 net the muslin should be doubled lengthwise and 

 along a diagonal line passing from a to b as shown 

 in fig. i. The top of the net is marked off by 

 striking arcs across the ends of the muslin with a 

 radius equal to the length of the muslin and from 

 a and b as centres. The cones may then be com- 

 pleted by closing the sides with a French seam. 

 If no bucket is desired at the end of the net it 

 may be closed by the seam e /. The condensation 

 and transfer of the catch to a bottle for preserva- 

 tion is, however, more effectively and quickly 

 accomplished if a bucket is used. The place at 



Fig. 1. 



which the attachment of the bucket should be 

 made can be indicated by striking the arc g h, 

 equal in length to one-half the circumference of 

 the bucket. The tip of the net may then be cut 

 off at ij and the muslin slit along the dotted lines 

 to allow for the fitting and fastening of the bucket 

 in place. The top of the net is finished by sewing 

 on the headpiece (fig. 2), which is made of a double 

 strip of strong linen cut bias and having a heavy 

 cord sewn in the upper margin. The net is fastened 

 to the ring which supports the mouth by a series 

 of overcast stitches of heavy thread. The ring r 

 should be made of spring-brass wire. At equi- 

 distant points upon it are soldered three pairs of 

 hips (h) or wire rings, which serve to hold the draw- 

 lines (d I) in place. At the junction of the draw- 

 lines a short cord serves as a weight-line (w I), to 



which a weight can be attached when towing in 

 deep water. An inexpensive bucket can be made 

 of sheet copper in the form of a cylinder three 

 inches in height and two inches in diameter. Two 

 light wire rings (r and r', fig. 3) are soldered round 



Fig. 2. 



the upper end of, and hold in place between them, 

 the string s, which ties the lip of the net to the 

 bucket. The bottom of the bucket b is formed 

 by an obtuse truncated cone of copper which 

 meets the sides of the cylinder an inch above its 

 base. At its centre is an opening half-an-inch in 

 diameter, which is continued in a short tube (t) 

 which reaches almost to the bottom of the bucket 



-V 



■f-i 



Fig. 3. 



and is obliquely pointed, forming a drip point (</ />). 

 The opening is closed by a rubber cork, the wire 

 handle of which projects slightly above the top of 

 the bucket. 



