410 MR E. M. WEDDERBURN 



launch Sunbeam, taking series of temperatures at various points en route with the 

 primary object of determining the temperature distribution of the loch and the 

 direction of the isotherms, with reference to the effect of winds. Towards the middle 

 of September a small decked fishing-boat was anchored off Fort Augustus in 250 feet 

 of water. This yacht, which was christened the Rhoda, was fitted out specially for 

 the observation of temperature by electrical means. In the boathouse of the Abbey 

 at Fort Augustus, which was put at the disposal of Sir John Murray for this and other 

 purposes, there was installed a Callendar electrical Recorder. This recorder was 

 connected with the Rhoda by means of a cable consisting of four insulated wires 

 as leads for the platinum resistance thermometers, which were operated from this boat. 

 These thermometers could be lowered to any desired depth and then connected with 

 the recorder on shore by means of the cable. Numerous difficulties were experienced 

 with this apparatus, but these need not be detailed here ; in consequence of the 

 practical difficulties which arose it was not always possible to place complete reliance 

 on the records obtained by its means. It was not possible when designing the 

 instrument to foretell all its requirements, and probably considerable modifications 

 could with advantage have been introduced. In place of a platinum thermometer it 

 was possible to connect with the recorder a bolometer or Sunshine Receiver. This 

 Sunshine Receiver was specially constructed to be capable of immersion in 

 considerable depths of water, with the object of determining to what depth the 

 effect of the sun's rays was directly felt, and also to detect, if possible, radiation 

 from the loch. 



It must be confessed that this elaborate and costly apparatus did not come up to 

 our expectations, although by its means considerable light was thrown on several 

 phenomena which would have otherwise been inexplicable. Great advantage was, 

 however, taken of the Rhoda. Not only was it possible by means of this boat to 

 observe in almost any kind of weather, but it was also possible to observe at all hours 

 of the day or night; and during August 1904 a long series of observations was made 

 by observing every two hours both day and night. In September 1904 several stations 

 were established along the loch at which simultaneous observations were made three 

 times a day, as it was then known that the original mode of arriving at the temperature 

 distribution of the loch by cruises in a steam launch was open to grave criticism. These 

 cruises unavoidably occupied the greater part of a day, and, in view of our results, it could 

 not be maintained that the distribution of temperature shown by the observations even 

 approximately represented the true state of affairs at any point of time, and it was 

 found impossible to apply corrections to the observations which would make them 

 comparable to observations made simultaneously at different points. Towards the 

 end of September the work by members of the Lake Survey was discontinued, but it 

 was enthusiastically taken over by members of the Order of St Benedict * at Fort 



* In particular, the observations were in charge of the Eev. Fr. Cyril von Dieckhoff and the Rev. Fr. 

 Odo Blundell. 



