TIDES AND CURRENTS 



confined waters during the winter and spring months, 

 gives a unique opportunity for such observations, im- 

 possible in open waters. The ice-surface atfords a plat- 

 form on which to erect any tide-observing instrument, 

 which, while rising and falling freely with the tides or 

 other dishevelling agencies, is undisturbed by any lateral 



Diagram showing the Principal Parts of the Tide-gauge 



W = the weights, the larger one as anchor, lying on the sea-bottom, the smaller one (the 

 object of which is to keep the line taut at all times) on the free end of the line, below the 

 lever : L = the long bamboo lever for reducing the scale ; T = two legs of the bamboo 

 tripod, supporting the pulley over which the wire passes ; D = the drum on which the 

 record is made. The recording part of the apparatus is more complicated than the dia- 

 gram indicates. It will be described in detail in the scientific publications. 



movements. By the combined efforts of most of the 

 scientific staff, and the skilful hands of our engineer. Day, 

 a form of tide-recording instrument was devised and 

 made. It was set up on the ice of Backdoor Bay, about 

 one hundred yards from shore, by Dr. Mackay arid 

 Professor David. 



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