Air. 



Water. 





84-5° 



85-5° 



1-02311 



85-4° 



86° 



1018 



85-5° 



86-5° 



1021 



... 



86-5° 



1-020^ 



... 



86-5° 



1021 



... 



86-5° 



1-023^ 



... 



86-5° 



l-023^\ 



1887.] of the Surface Sea-ivater at the Sandheads. 17 



Temperature. Specific gravity, 



June 18th, 1886 Saugor Roads (bound out) 

 „ 20th „ Eastern Channel Light. W. 



by N., 4 miles 

 „ 21st „ Eastern Channel LigVt. 



North, 9 miles 

 „ 22nd „ Intermediate Light (bound 



in) 

 „ ,, „ Lower Gasper Light 

 „ „ „ Upper Gasper Light 

 „ „ „ Saugor Roads 



Note : — The Saugor Roads observation of the 18th was taken on the 

 last quarter flood, and that of the 22nd on the last quarter ebb. 



By this we have an accumulation of salt in Saugor Roads of 

 •005y*g^ over and above what was found in the water at the Eastern 

 Channel Light Station, thirty-six miles farther seawards, only a day 

 or two previous. There was a set to the westward of the yellowish 

 green water at the Sandheads, or Eastern Channel Light Station, on the 

 20th and 21st June, which would probably account for some of the above 

 great differences in the relative specific gravity, though not for all. We 

 also see by the above observations that at a distance of eight or nine 

 miles dead to seaward of the above station, and well out in the 20 fathom 

 line of soundings, there was an increase in the density of the sea water 

 of '003, this indicating that the induced lateral stream of fresher water 

 from the eastward was not of necessity a very broad one : the reason of 

 which I will attempt to explain further on, when I come to speak of 

 the influence which the Swatch of no Ground doubtless has upon this 

 westward set of the outside waters of the littoral. But even out there, 

 we see the density did not exceed that of the sheltered muddy waters 

 at the Lower Gasper Light Station, thirty-three miles farther north, and 

 that it fell far short of that of Saugor Roads. 



With reference to this very interesting question of the increased 

 specific gravity of these inshore waters of the littoral during the dry 

 months of the year, it is worthy of note that our late senior pilot, Mr. 

 C. Smyth, used to say his long experience led him to believe that the 

 reason vessels so seldom ' felt the ground,' or ' bumped,' in the Gasper 

 Channel, — when their known draft of water, depth given by the charts, 

 height of sea-surface above ' lowest low water,' or zero, as given by the 

 tide table, and allowance for swell running, showed they had apparently 

 not much water to spare under their keels, — was, that some sort of 

 meeting of the tidal currents piled up the water, as it were, about 

 3 



