TEMPERATURE OBSERVATIONS IN LOCH EARN. 



757 



travelling surface waves break on a shelving beach. If there is such breaking of the 

 density wave strong currents will probably occur, and the conjunction of strong 

 currents with rapid movements of the isotherms has been noted on page 755. 



The observations during the week following the series of 13th to 15th August do 

 not call for remarks other than have been already made in the discussion of current 

 observations, but during the week arrangements were made for the final series from 

 24th to 29th August. For the first three weeks the number of observers never 

 exceeded 5, but for the last series 12 observers were fully employed. During practi- 

 cally the whole of the time 3 thermometers were kept in use on each boat, and about 

 36 temperature observations were made hourly in each boat by 2 observers. It may 

 be mentioned, as indicating the strenuous nature of the work, that the observers 

 who were on night duty observed for 12 hours without intermission. On 28th August 

 for 12 hours observations were made at a third station marked 3 on the map. 



Metrts 10 



Fig. 12. — Observations at Station 3. 



In all, during the week, about 9000 temperature observations were made, and 

 these are shown on the lower half of figs. 10, 11, and 12, which represent the 

 variation of temperature with time at various depths. Curves of the variation of 

 temperature with depth at any moment, 3000 in number, were then drawn from 

 these curves for intervals of 5 minutes during the series, and from these tempera- 

 ture-depth curves the curves showing the oscillations of isotherms were drawn, being 

 the upper portions of the diagrams. 



Notes showing the weather conditions during the series will be found on fig. 10, 

 but during most of the time, with the exception of the last day, there was an absence 

 of strong winds, and the conditions were as suitable for observing a temperature 

 seiche as one could well hope for. 



On 22nd August, as has been seen, there was a strong westerly wind, and the 

 surface temperature at Lochearnhead fell from over 15° C. to 9" 6° C, thus showing that 

 a large quantity of warm water had been transferred to the east end of the loch. 



On the 23rd the west wind still continued, but was not so strong. Unfortunately, 

 no temperature observations were made on that date, as the observers were having 



TRANS. ROY. SOC. EDIN., VOL. L, PART IV (NO. 19). 104 



