726 fisheries of the united states. [82] 



Brass dory compass. 



Diameter, 3 inches; depth, if inches. U. S. Fish Commission. 

 57,085. Carried on dories in foggy weather to enable the fish- 

 ermen to find their vessels. 



Patent dolphin ship's log. 



Brass, with dial ; English make. Length, 18 inches; spread of fans, 

 6 inches. U. S. Fish Commission. 39,383. Used to ascertain 

 the distance run by a vessel. 



Patent taffrail log. 



Two sections, (1) the fan, which is towed astern of the vessel and 

 is attached to the end of a line, the other end of which is fas- 

 tened to (2) the indicator or register, that is secured to or near 

 the taffrail. The advantage of this is that readings may be 

 taken from the log without hauling it in, as must be done with 

 all others. John Bliss & Co., New York. 



"The following are some of the special advantages found in using 

 the taffrail log: (1.) The dial of the log can be easily inspected 

 at all times, Which is particularly convenient when changing 

 the course of the vessel, the necessity of hauling in being 

 avoided. (2.) The rotator only being overboard and a smaller 

 line used, the strain upon the line is about one-quarter of that 

 of the submerged log, which is variously estimated at 40 or 50 

 pounds, sufficient to decrease the speed of the vessel to some 

 extent; besides, the greater strain often causes the breakage 

 of the line and tne loss of the entire log. (3.) This log will be 

 found, ultimately, the cheapest, because only the rotator is ex- 

 posed to danger of loss, and when lost, can be replaced at tri- 

 fling cost. (4.) The substantial manner in which these logs are 

 made, and the fact that the registering apparatus is not exposed 

 to the action of salt water, may be taken as a guarantee that 

 they will last far longer than is possible with any submerged 

 log. »(5.) The liability of having the log ruined, or at least dis- 

 abled, when crossing shoals, by striking the bottom, or being 

 filled with sand, is avoided. (6.) The state of the log being 

 readily seen, prevents the danger of overrunning a given dis- 

 tance when on any course. (7.) Fouling with sea-weed is avoided 

 by the gradual taper of the blades, and the freedom from ob- 

 structions, such as knots or eyes. (8.) This log will indicate 

 accurately at a lower speed than any submerged log, because 

 there is less slip, owing to the spiral form of the blades of the 

 rotator. (9.) The greater part of the damage caused by haul- 

 ing in is avoided in this log, as that is so seldom required; 

 besides, the blades, being spiral, are much stronger." (J. Bliss 

 &C0.1 



