458 POWER OF CALCULATION. 



instinct. Various birds can be easily deceived by artificial 

 reversal of the natural phenomena of light. 



The duration of a master's sleep is estimated, and cor- 

 rectly, by certain sporting dogs and by some birds, such as 

 the hornbill ; and if he oversleep the usual time, they awake 

 him : thus the tame hornbill awakes its master for breakfast 

 (Houzeau). 



Certain clever, trained dogs have been described as 

 having a knowledge of the hours on the watch or dock as 

 being able to indicate the hour by reading the dial of either 

 or both (Watson). But there is obviousl}-' no necessary con- 

 nection between such a feat and that calculation of time- 

 whatever be its nature by which so many of the operations 

 of domestic animals are regulated. 



There is at present no evidence to show whether the dog 

 or other animals can count in any way, or otherwise distin- 

 guish, the different hours struck by a clock, which would 

 involve the faculty of numeration. 



Without rigidly observing certain hours, there are various 

 animals that do certain things in the morning, at noon, and 

 in the evening, at dawn or sunrise, and at sunset or the 

 approach of night. Wherever dairy cows go to and from pas- 

 ture in summer, they may be observed gathering themselves 

 spontaneously at sundown at or near the gate of their pad- 

 dock, waiting to be let out in order to go to their byres for 

 the night. I have seen this over and over again myself in- 

 deed, sometimes daily during the summer months. 



Equally noticeable and notorious is the noon exodus of 

 dairy cows from a certain town common in my own neigh- 

 bourhood. The animals do not require to be collected or 

 called ; they collect themselves at the proper time and find 

 their own way home. In both these cases of noon and 

 sunset migrations the animals may be guided by the light 

 or heat proceeding from, or by the position of, the sun- 

 when there is a visible sun to guide them. But this expla- 

 nation scarcely suffices, considering that (1) the habit is a 

 daily one, not determined by or depending upon sunshine ; 

 (2) in so murky, changeable, pluvious a climate as that of 

 Scotland brilliant sunshine is not a common phenomenon 



