258 Proceedings of Royal Society of Edinburgh. [june 6, 
Table were all determined by the delicate hydrometer, and are 
reduced to their value at 1 5°*56 C. Weather was dull, with some 
showers, until 13 h 0, thereafter bright and dry. 
Table YI. — Observations off Alness Point , Cromarty Firth. 
Date. 
Hour. 
Wind. 
Tide. 
Depth. 
Temperature. 
Density. 
Air. 
Surface. 
Bottom. 
Surface. 
Bottom. 
fm. 
O 
O 
O 
Aug. 12 
ll h 0 
WSW.,2 
1^ h. eb. 
9 
54-4 
53-8 
1-02431 
1-02480 
> 5 
12.0 
WSW.,2 
Ol 
■“2 55 
9 
56-2 
55-3 
53-8 
1-02357 
1-02482 
?? 
13.0 
0 
°2 55 
r-W 
OO 
57-8 
55-3 
54-0 
1-02373 
1-02470 
14.0 
0 
41 
*2 55 
8 
... 
55*3 
54-3 
1-02370 
1-02422 
5? 
15.0 
0 
51 
55 
6 
58-0 
55-4 
( 
55-2 
1-02319 
1-02369 
16.0 
0 
L. W. 
64 
58 7 
56T 
55-8 
1-02224 
1-02344 
? ) 
17.0 
E., 2 
1 h.fld. 
64 
58-3 
56-4 
55-2 
1-02162 
1-02336 
> 5 
18.0 
E.,2 
2 „ 
6| 
56-0 
561 
55-2 
1-02290 
1-02391 
? J 
19.0 
0 
3 „ 
7 
56-3 
55*7 
55-0 
1-02317 
1-02411 
> 5 
20.0 
0 
4 „ 
7 
53-9 
54-9 
54*0 
1-02396 
1-02472 
Note . — The position was changed a few yards nearer the north shore between 
the 14 h 0 and 15 h 0 observations. 
This series also shows the temperature and salinity to be in 
close association. Hence, considering either the one quantity or 
the other, the relative movements and gradual mixture or separa- 
tion of the warmer and fresher upland water and the colder and 
salter sea water may be traced out. The salinity at the bottom 
remained constant for about three hours after high water, then 
gradually diminished until low water, and again gradually in- 
creased. Surface salinity remained practically unchanged, and 
very near that of the bottom water, until two hours before low 
tide, when it began to diminish, and came to a minimum (the 
surface temperature coming to a maximum) one hour after low 
tide. This marked the period of greatest difference between 
surface and bottom salinity; that at the surface proceeded to 
increase, presumably until high water. These observations show 
that flood-tide sets in first at the bottom ; that the salt water first 
