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XIX. — Temperature Observations in Loch Earn. Part II. By E. M. Wedderburn, 



D.Sc, and A. W. Young, M.A., B.Sc. 



(Read July 6, 1914. MS. received October 6, 1914. Issued separately April 13, 1915.) 



Introductory. 



The observations which were made in Loch Earn during August 1911 and 

 described in the Trans. Roy. Soc. Edin., vol. xlviii, p. 629, demonstrated that in that 

 loch there was during autumn a fairly definite temperature or density discon- 

 tinuity, and suggested that the loch was a peculiarly suitable one in which to 

 observe in greater detail the boundary waves occurring at the discontinuity. The 

 previous investigation had for its main purpose the demonstration of the existence 

 of standing oscillations at the discontinuity, and in that was entirely successful. The 

 observations showed, however, that in addition to the primary standing oscillations 

 there were other less regular movements about which the observations gave little 

 information, as they were not made at sufficiently close intervals of time. 



The current observations which were made in 1911 gave a disappointingly small 

 amount of information, and it was hoped that with improved methods of observation 

 the nature of the boundary changes which occur would be more evident. 



Plan of the Investigation. 



A considerable grant from the Sir John Jackson Tait Memorial Fund of the 

 University of Edinburgh made possible an extensive investigation and the employ- 

 ment of new instruments. We were fortunate in securing the collaboration of a 

 number of those engaged in the previous investigation in Loch Earn, who were 

 therefore experienced in the work required of them. In addition to the authors, 

 Messrs T. G. Ironside, M.A., B.Sc, W. G. M'Ewen, M.A., and A. J. Eoss, M.A, 

 were engaged in observing during the whole of the period of observation, and 

 assistance was given for part of the time by the following, viz. : Messrs James 

 Chumley, Wm. Gillon, M.A, B.Sc, W. Jardine, M.A., B.Sc, R. M'Callum, 

 J. Mackie, M.A., B.Sc, W. R. M'Lennan, A. S. Tennant, M.A., I. E. de Watte- 

 Ville, M.A. To all of these gentlemen cordial thanks are due for enthusiastic assist- 

 ance ungrudgingly given. 



It was decided to concentrate the work at the Lochearnhead end of the loch. 

 To make observations at several points on the scale attempted at Lochearnhead 

 would have been impossible, and it was thought that with the instruments which 

 were available numerous observations at two points about half a mile apart at the 

 end of the loch would yield most information. 



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