NATURAL HISTORY SOCIETY OF GLASGOW. 179 



II. — On Marine Dredging. By Mr David Robertson. 



Plate II. 



The foUomng remarks are intended only to point out a few 

 conditions necessary to successful dredging, in the hope that they 

 will, in some measure, aid the student who has included the 

 dredge in the programme of his approaching holiday excursions, 

 and show how he may avoid some of the common sources of 

 disappointment. The remarks apply only to the use of the dredge 

 in a small boat, rowed by one or two men. The dredge to many 

 may not appear the most pleasant instrument of research. With 

 its fittings it is cumbersome, and it is wet and toilsome to work; but 

 still, to the marine zoologist, it is indispensable and full of interest. 

 None but those who have experienced the glowing excitement 

 caused by the turning out of a well filled dredge, can know any- 

 thing of the pleasurable suspense till the next haul is drawn up. 

 It would he difficult to lay down rules for dredging operations, 

 however simple, that would not be subject to modification; our 

 success at all times depending less or more on our aptitude to 

 meet varying circumstances as they arise. 



First of all choose a good day, as little or no progress can be 

 made with the dredge in a small boat when the sea is rough. 



The Boat. — The size of the boat should be from fourteen to 

 sixteen feet keel, but not less than thirteen feet. The objection to 

 a smaU boat does not wholly apply to its capacity, for it may be 

 large enough for one person when he chooses to go by himself, 

 but there is great difference of power on the dredge in the large 

 compared with the small boat. A small boat will be stopped 

 short when the way is on it by an obstacle that would be readily 

 overcome by a larger boat. 



Although it is desirable at all times to have strong arms at the 

 oars, when the dredge is tugging doggedly behind, still I have 

 had many successful dredgings by myself. It is surprising what 

 can be done by a single person in a boat, pulling at his ease, 

 taking what advantage he can of both wind and tide, with nothing 

 to control him, sitting, leisurely and carefully examining the 

 contents of each haul. The way on the boat is, meanwhile, 

 making some progress with the dredge, which has been again 

 cast overboard, and is at the same time preventmg the boat from 

 drifting off the proper ground till the oars are applied. In regard 

 to the build of the boat, if you have a choice, prefer one with a 



