152 



Part III. — Seventeenth Annual Report 



There are parts of the shores of Loch Achray that are fringed with a 

 rich growth of vegetation which might be expected to afford shelter to a 

 numerous Entomostracan fauna ; but here, as in some other lochs where 

 similar favourable conditions exist, it was found that the young trout 

 and minnows were also cognisant of this fact, for shoals of these tiny 

 marauders were observed busy at work trying to secure a share of the 

 Entomostracan food sheltering amongst the aquatic vegetation. It is our 

 experience, as it is the experience of others, that where these small fishes 

 are plentiful the shore Entomostraca are not so numerous. 



Loch Achray, like the other lochs, was examined on four different 

 occasions. The method of examination was also similar, and the follow- 

 ing is a record of the results obtained. 



Temperature and other Physical Observations. 



The annexed Table shows the temperature and other observations as 

 recorded during the four different examinations of Loch Achray. The 

 observations were taken well off shore, but not so far off as to be in the 

 line of the river current. 



Table showing Temperature and other Physical Observations. 



Date. 



Hour. 



Temperature. 



Wind. 



Weather. 



Surface Movement 

 of Water. 



Air. 



Surf. 



Water. 

 5Fms. 



lOFms 



Direction. 



Force. 



1897. 





Begs. 



Degs. 



Degs. 



Degs. 











Sept. 10 



Noon. 





57-0 



55-0 



55-0 



Variable. 



Light. 



Mild ; fine. 



Slight ripple. 



Nov. 27 



Noon. 



45-2 



45-9 



45-9 



46-0 



Westerly. 



Squally. 



Hvy show'rs 



Rough. 



1898. 









26ft. 







of rain. 





Mar. 17 



11 a.m. 



49-4 



40-8 



40-9 





S. Westerly. 



Squally. 



Showery. 



Rough. 



June 28 



12. 30 pm 



78-5 



64-1 



52-6 



48-8 



Calm. 





Fine; warm. 



Smooth. 



When the loch was tow-netted in November, the wind, though moderate 

 at first, increased so much that our boat had to be run ashore half way 

 down towards the east end of the loch ; and on 17th March the weather 

 was again so stormy that it was not considered advisable to proceed to the 

 usual distance off shore, and on this occasion, therefore, a sounding of 

 only twenty-six feet was obtained; on the other hand, soundings of ten 

 fathoms were obtained in September and November, and when the loch 

 was examined in June no bottom was found at sixty-four feet. 



The temperature readings for this loch are in some respects different 

 from the other lochs examined, but probably this is owing to the some- 

 what different physical conditions of Loch Achray. Comparison with 

 other lochs can therefore only be made within certain limits. Loch Achray 

 is comparatively small and narrow, and, except in dry seasons, there is a 

 moderately large current of water continually passing through it. This 

 current sets up movements in the water that tend not only to equalise the 

 temperature, but also to reduce it. This is partly confirmed by the 

 observations contained in the Table. Loch Achray is situated not only at 

 a lower level than Loch Katrine, and is largely supplied with water from 

 that loch, but it is also much smaller and more sheltered; its temperature 

 might therefore be expected to be at least as high as that of the loch from 

 which so large a proportion of its water comes. We find, however, that 



