POWEK OF CALCULATION. 455 



2. A power of measurement of intervals of minutes, 

 hours, days, or weeks. 



3. A keen observation of hours, days, and seasons ; of the 

 progress of the sun, of the sequence of light and darkness. 



4. Notions or ideas of time or duration. 



5. Precision in marking time. 



6. Distinction of time by observation and inference 

 (Watson). 



7. Appieciation of such natural phenomena as dawn, noon, 

 and sunset. 



8. Observation of man's movements and of the circum- 

 stances or things that mark certain hours of the day and 

 days of the week in short, of concomitant phenomena. 



9. A sense of periodicity, which gives rise to punctuality 

 or regularity. 



10. Knowledge of the succession of events, the possession 

 of what phrenologists call the faculty of eventuality. 



Some of these explanations or suggestions are satisfactory 

 in certain cases, others are plausible, while others again are 

 problematical and destitute of any sort of proper proof. On 

 the whole, it must be confessed that our knowledge of the 

 various modes by which animals acquaint themselves with 

 hours and days is far from being complete or satisfactory. 

 Hence it offers an excellent and interesting field for experi- 

 mental enquiry. 



We are, however, in possession of a large body of facts 

 showing that animals have a certain knowledge of time, and 

 it is desirable that illustrations should be given of the various 

 kinds of their time-knowledge with the modes in which they 

 display it. Nor is it irrelevant, in the present state of our 

 information on the subject, to consider some of the suggested 

 explanations that offer themselves, or that have been offered. 

 One of the commonest kinds of time-knowledge exhibited 

 by the lower animals the kind which most strikes man is 

 that which relates to the hours of the day, especially to man's 

 meal hours. Various tame, or even sometimes wild, animals 

 conie to be fed at the meal hours of a family, and they make 

 no mistake as to these hours. I have several times noticed 

 this myself in the case, for instance, of the common sparrow, 



