THE HABITS OF THE SALMON. 39 



during the month of January, 1887. The test was 

 made in both cases just above where the waters 

 meet at Navan. Here is the result. 



It will be seen from the above statistics that 

 the temperature of the water in the Blackwater 

 averaged three degrees higher in January than that 

 in the Boyne. And so I can satisfactorily explain 

 why salmon appear in the former river earlier than 

 they do in the Boyne above Navan. 



Independently of other instances to which I could 

 well refer, we have already three rivers in Ireland 

 through which the earliest spring salmon directly 

 travel for the upper waters in spite of all obstruc- 

 tions. But this is not surprising, although with 



