NATURAL PHILOSOPHY. 



169 



diurnal lunar tidal-wave on Lake Michigan, at Chicago; and thirty minutes 

 after the period of the moon's meridian passage as the average time of lunar 

 high water. These are the results from all the observations made during the 

 six months' series. 







TABLE I. Showing the half -hourly (and at two periods the quarter-hourly} 

 coordinates of altitude of the average semi-diurnal lunar tidal-wave at Chicago, 

 on Lake Michigan, derived from the whole 9,184 observations made. 



TABLE II. Shoiuing the half-hourly (and at two periods the quarter-hourly) 

 coordinates of altitude of the average semi-diurnal lunar tidal-wave at Chicago, 

 on Lake Michigan, as derived from 8,995 out of the 9,184 observations made 

 between January 1st and July 1st, 1859. 



l Lunar low-water. 2 Moon on Meridian. 3 Lunar high-water. 



4 Slightly discrepant, owing to a preponderance of unfavorable winds at this 

 particular period. 



