232 HINTS FOR COLLECTING. 



But the dredge 



" With its iron edge, 

 And its mystical triangle, 



And its hided net with meshes set, 

 Odd fishes to entangle ! ", 



surpasses all other methods of investigating the fauna of 

 the ocean. Its history, as an instrument of scientific re- 

 search, dates from the publication of O. F. Muller's great 

 posthumous work, the c Zoologia Danica/ in 1788. 

 The oyster-dredge is much more ancient, and is familiar 

 to every one. The principal difference between this and 

 the zoologist's dredge consists in the latter having a 

 blade or scraper on each side (so that it always falls to 

 the bottom in the right position), and it has also a 

 closely netted bag within the hide or outer net ; iron 

 ring work does very well to contain oysters, but not the 

 small miscellaneous treasures of the zoologist. The 

 weight of the dredge varies from 14 lbs. to f cwt., ac- 

 cording to the depth of water in which it is worked. In 

 bays and sheltered parts of the sea, where the depth 

 does not exceed 20 or 30 fathoms, a small sailing-boat, 

 or one with oars, from 50 to 100 fathoms of line, and 

 two or three men will answer the purpose ; for deeper 

 water a larger vessel and a proportionate supply of rope, 

 with a more numerous crew, are necessary. In the latter 

 case, if a sailing vessel be employed, she is made to lie 

 to (the helm being put up) , with shortened sail and her 

 head close to the wind. Do not attempt to dredge 

 against the tide : you may dredge with or across it. 

 When the ground is rough, the dredge is likely to catch 

 in a stone, and may be easily lost. To prevent such an 

 accident, the end of the rope is fastened, not to the ring 

 which holds the arms together and forms the point 

 of the triangle, but to one side of the dredge ; and the 



