620 MR E. M. WEDDERBURN ON THE TEMPERATURE SEICHE. 



42 metres and a length of 17 kilometres. The district was well known to Halbfass, 

 as he had made previous surveys and seiche investigations there, and the author is 

 much indebted to him for the manner in which he made arrangements in advance 

 which ensured the smooth progress of the observations once they were begun. Professor 

 Halbfass also secured numerous assistants : Friedrich Knieriem, Bad Neuheim, and 

 Joseph Muller, Aachen, students of geography, observed during the whole period, 

 and Herr Piper, bailiff of the Royal fisheries in the lake, helped them. Assistance 

 was given for various periods by the following gentlemen : Herr Referendar Herms, 

 Tempelburg, Herr Phillip, and Herr Berkholz of Pyritz. Herr Dorow, the lessee 

 of the fishings, frequently put his motor boat at the service of the observers for 

 communication between the different stations, and this was a great convenience. To 

 all these the author wishes to express his thanks * for assistance ungrudgingly given. 

 The Survey party from this country besides the author included Mr W. E. Ogilvie, 

 Broughty Ferry, and as boatman Mr Wm. Macdonald, Fort Augustus. 



§ 4. The Madusee is very different from Scottish lakes, for the shores at every 

 point shelve ver}^ gradually, and in most places there is a fringe of reeds, at times 

 of considerable breadth. The surrounding country is flat, and winds can therefore 

 blow over the lake from any direction. The basin of the lake is fairly uniform, and 

 there is no sudden shallowing. There is, however, an unfortunate constriction near 

 the centre of the lake, otherwise it would have been excellently adapted for observing 

 temperature oscillations, in spite of the shelving shores. It will be seen in the 

 sequel that shelving shores are not nearly so important for temperature oscillations 

 as they are for the ordinary seiche, and, on the whole, the observations which were 

 obtained were successful and should remove all reasonable doubt as to the existence 

 of temperature seiches. Between the views of Professor Halbfass and the author 

 there is now close agreement. 



§ 5. Preliminary observations were made on 24th July to determine roughly the 

 nature of the temperature distribution in the lake, and it was found that there was 

 a clear Sprung schicht or temperature discontinuity which promised interesting results. 

 Three observation stations were determined on, viz. — Moritzfelde at the north end, 

 Seelow at the centre, and Werben at the south end. At Werben, in order to get a 

 sufficient depth of water, it was necessary to observe at a considerable distance from 

 the end of the lake. The positions are marked on the sketch-map, fig. 1, by a cross. 

 On this map depth contours are drawn for each 10 metres. It will be seen that there 

 are numerous villages along the shores of the lake ; but the roads between these 

 villages were very bad, which made communication between different parts of the 

 lake difficult. The observations at Moritzfelde were under charge of Herr Knieriem 



* Acknowledgment is also made to the following institutions which lent instruments to Professor Halbfass : — 

 The Deutsche Seewarte for a reversing thermometer, the Kgl. Preuss. Meteorological Institute for a wind-meter, and 

 the Institute of Meereskunde, Berlin, for current-meter and sounding lines. From this country several thermometers 

 were lent from the Challenger Office by Sir John Murray, K.C.B. 



