and Astronomical Notices. 171 



which can be undertaken much more securely from measures 

 of angles of position rather than from those of distance. The 

 simple vane, however, of course, admits of much improve- 

 ment, being too liable, like the Lind's gauge, to excessive 

 momentary alterations, if it has any sensibility at all ; and 

 this it should possess in an extreme degree, or, like many a 

 rusted old church weathercock, it may be utterly insensible 

 to all slight variations of the atmosphere. There seems, 

 however, to be no reason why Dr Robinson's method of curb- 

 ing the violence of his vane should not be employed on ship- 

 board ; and then with this, and the revolving anemometer, 

 the two respective elements of the wind might be read off to 

 fully as great an amount of accuracy as either the ship could 

 be steered and the compass kept constant to, on the one 

 hand ; or the speed of the vessel be determined to, on the 

 other ; and probably the compass might be improved and 

 steadied when tossed about and forced to vibrate much, by 

 the application of the Doctor's curbing apparatus in a simpler 

 shape, while the revolving hemispheres would certainly be a 

 great improvement on Massey's patent log with inclined 

 vanes, for while the value of the revolutions of these cannot 

 be determined by any measure or examination of the ma- 

 chine itself, which can well be made on board ship, and may 

 vary every day, from very small and otherwise imperceptible 

 accidental injuries, and may not continue constant at different 

 velocities and temperatures, — the value of a revolution of 

 the hollow hemispheres may be ascertained at once by any 

 carpenter's rule, and nothing short of an actual and visible 

 smashing of them is likely to alter that proportion sensibly. 

 Improved Forms for Log-books. — To suggest any alteration 

 in the form of the ship's log-book, may not be received by 

 sailors very readily ; but still, as they have themselves been 

 making various alterations of late, and hardly seem satisfied 

 yet, even for their own purposes, — while for those of science, 

 which many among them are extremely anxious to subserve, 

 the present forms are utterly inconclusive, — some general 

 principles may be indicated, which having been found useful 

 in more exact and extensive observations and computations 

 on shore, can hardly but be of aome service also at sea. 



