354 



Appendices to Fifth Annual Report 



Considerations of salinity and also of temperature lead to a distinction 

 being drawn between various parts of the Firth. Between Inchkeith and 

 the sea there is a constancy of salinity and of temperature from point to 

 point, and from surface to bottom, and from high to low tide, that stands 

 sharply in contrast with the region between Inchkeith and the river, where 

 there is rapid change in all conditions from many causes. These two 

 very different parts of the system I have proposed to call the Firth proper 

 and the Estuary. The upper limit of the estuary cannot be fixed by 

 reference to points on shore. It may be taken as the line to which tidal 

 variations of salinity extend, as distinct from mere variations of level, 

 such as might result from the damming back of fresh water. The state 

 as regards flood of the river and the height of the tides are determining 

 conditions of this limit, and as these vary the limit of salinity will vary 

 also, although, from such observations as have been made, the range along 

 the banks may be comparatively short. Further observations are neces- 

 sary to give certainty on this point. Inchkeith is obviously the boundary 

 between estuary and firth, and the line dividing firth from sea lies some- 

 where about or beyond the Isle of May. 



In some river entrances, such as that of the Tay, there appears to 

 be no firth, the estuary uniting with the sea : and in others the estuary 

 even is wanting, the river running directly into salt sea water. In the 

 two latter cases the surface water is much freshened in the immediate 

 vicinity of the discharge, but the lower strata are fully salt. Near a firth 

 like the Forth the surface water of the adjacent sea is but little reduced 

 in salinity at the place of contact, but, on the other hand, the whole mass 

 of water to the very bottom is freshened in nearly the same proportion. 

 For example, salinity of 3*50 per cent, is found at the bottom quarter of 

 a mile off the mouth of the Spey, but is not reached until 75 miles off the 

 mouth of the Firth of Forth. 



iPPENDIX F.— No. XV. 



KEPORT ON THE ST ANDREWS MARINE LABORATORY, 

 No. IV., from 1st January 1886 to 31st December 1886. By Prof. 

 M'Intosh, F.R.S. 



1. Structural Changes in the Laboratory. 



During the year several gas-jets and stands, a fresh-water pipe and acces- 

 sories, two additional windows, a few tables and shelves, have considerably 

 increased the conveniences for work. Canvas shades have also been pre- 

 pared for some of the western windows and the high-level tank. A long 

 leaden pipe, with fifteen nozzles, has also been fitted in the tank-room, 

 Twice during the year, viz., in January and October, the vulcanite pipes 

 in wooden boxes leading down to the beach were damaged by heavy seas. 

 This is due to the fact that the posts which support them are not suffi- 

 ciently sunk in the hard ground (clay) beneath the sand. A few deeply- 

 placed beams would obviate this risk. 



2. Additional Apparatus and Books. 



An important new feature in the equipment of the Laboratory is the 

 acquisition of a small fishing boat or yawl, 21 feet long. This boat is 

 worked by the laboratory attendant, and has been of great service in 



