668 TIDES AND CURRENTS. 



Usually no observations have been made on the currents in the 

 Arctic regions, except where the sea is clear of ice, because of the 

 want of apparatus. 



(4.) Much more perfect apparatus for registering and even 

 recording the tides may be fitted within the ships ; there seems 

 to be no reason why the height of the tides should not be con- 

 tinually registered on a revolving cylinder as in various ports^ 

 according to the plan adopted by Sir Wm. Thomson. Fixing the 

 tidal apparatus within the ship, the rope, which is usually attached 

 to a float, must be attached to a stone at the bottom, and must have 

 a pencil or index attached to it, as in M. Koldewey's apparatus. 

 Thus the pencil will remain fixed, and the cylinder on which the 

 tidal curves are traced will rise and fall with the tide. Also the 

 currents in the sea might be registered and recorded by means of an 

 apparatus similar in construction to the apparatus devised by Dr. 

 Robinson for registering the rate of the wind, but with the cups at 

 the bottom in&tead of at the top of the shaft. The apparatus consists 

 of four hemispherical cups placed symmetrically in a horizontal 

 plane, and attached to a vertical revolving shaft. By means of 

 proper gearing, the rate of revolution of the shaft is recorded by a 

 pencil on a revolving cylinder. There seems to be no reason why 

 the rate of currents of water should not be registered by this 

 apparatus quite as accurately as the rate of the wind by means 

 of Dr. Robinson's apparatus. 



Even if the delicate apparatus for recording the currents con- 

 tinously cannot be conveniently applied on board the ships, it will 

 still be of very great importance to employ some such apparatus 

 as the revolving cups above described, and to apply to them an 

 index which shall enable the observer to record the rate of 

 revolution, and so to determine the rate of the current.] 



13. Voyage of the "Polaris" under Captain Hall. 



A comparison of the facts relating to this voyage are gathered 

 from Captain A. H. Markham's " Whaling Cruise to Baffin's Bay,"^ 

 and Clement Markham's *' Threshold of the Unknown Regions,'* 

 with the records of the discoveries of Dr. Kane and Dr. Hayes in 

 Kennedy Channel. 



p. 189.— In August 1871 the " Polaris" went from Cape 

 Shackleton (in latitude 74°, near Upernavik) to her extreme 

 northern point in 82° 16' N. (a distance of about 600 miles) in 

 five days (part of the way against a current of 1 knot an hour)^ 

 and was stopped by an insignificant stream of ice which might 

 have been easily passed through, while there was a magnificent 

 water-sky to the northward. The floes in Smith Sound were 

 small, and no icebergs of any size were seen north of 80° N., i.e., 

 north of Cape Fraser or the Humboldt Glacier. Like Dr. Hayes, 

 Captain Hall went northwards on the west side of Kane Basin 

 and Kennedy Channel, whereas Dr. Kane was proceeding on the 

 eastern side when he was caught in the ice in Van Rensselaer 

 Harbour, where he experienced very severe cold. 



