1908-9.] Observations with a Current Meter in Locli Ness. 635 
The examples referred to above are as follows : — 
Date. 
Velocity. 
Cm. sec. 
Depth 
Feet. 
Directions. 
1909 
Jan. 11 
37 
300 
15 S. 54 V . 50 
„ 18 
3-3 
150 
G S. 41 W , 90 
„ 20 
3T 
450 
18 S. 50 "YY . 120 
„ 21 
3 3 
450 
/ 108 * 80 W . 190 
\ X N. 60 E. 
55 5 ? 
4-2 
200 
15 S. 31 W . 110 
„ 23 
7-7 (?) 
400 
8 S. 55 W . 20 
„ 25 
37 
400 
f io 8 * 61 V . 100 
t X N. 60 E. 
„ 26 
3 7 
465 
13 S. 50 W . 80 
„ 27 
4*6 
465 
i 0 S. 48 W . 40 
95 55 
4-4 
400 
f 158 - 70 W .110 
l 52 A¥ . 140 
95 99 
3T 
300 
4 N. 60 E. 
Feb. 12 
6*4 
465 
22 S. 55 W . 60 
Summary of Results. 
From observations so complicated and, at times, apparently conflicting, it is 
difficult and dangerous to draw general conclusions, but it is thought that the 
following deductions are justified with regard to the currents in Loch Ness: — 
1. When the lake is of uniform temperature, then the direct current 
produced by wind is felt to considerable depths, and the return current is 
also felt in the deepest parts of the lake. 
2. When the lake has become stratified and the temperature discon- 
tinuity has appeared, the return current is nearly always found to be above 
the discontinuity, although there are indications of secondary currents in 
the same direction as the surface current below the discontinuity. 
3. When a wind follows a calm, or when the direction of the wind 
changes, the direct surface current is felt to a considerable depth ; but when 
the wind has been blowing for about twelve hours the return current asserts 
itself and the surface current is restricted to a narrower zone. 
4. When a calm follows a strong wind the isotherms tend to assume a hori- 
zontal position, and in consequence there is in the upper layers a current in an 
opposite direction to that of the wind which has previously been blowing. 
5. Towards the windward end of the lake the return current may take place 
very close to the surface. Towards the lee end it is found in deeper water. 
6. At the windward end of the lake there is complexity in the current 
coming to the surface. 
7. There are indications of secondary currents in the same direction as 
the wind below the temperature discontinuity when the lake is stratified. 
8. Cross currents are frequent and form part of the circulation of the 
lake, reducing the strength of the main return current. 
