134 A. W. Duff- — Secondary Undulations 



usually accompanied by marked oscillations at the other. Con- 

 spicuous examples are, Jan. 13th, 1898; Nov. 26 and 27, 

 1898; Dec. 23, 1898 ; Dec. 31, 1898 ; Jan. 1 and 2, 1899, &c. 

 The exceptionally strong undulations on these dates coincided 

 with severe storms from the south on the Atlantic. But this 

 connection is not quite invariable, e. g., on Aug. 14, 1898, 

 strong oscillations of 15 inches at Yarmouth were not accompa- 

 nied by any exceptional oscillations at St. John or Halifax. 



Turning now to a comparison of stations on the Atlantic 

 and stations on the Gulf of St. Lawrence, it is found that in 

 general no such connection exists. For instance, in my note 

 book, opposite each of the cases of marked oscillations at St. 

 John, Halifax, and Yarmouth, just enumerated, I have a note 

 of the state of affairs at St. Paul's Island, South West-Point 

 and Forteau Bay, and the notes, with two exceptions, are " no 

 oscillations," " particularly slight," " less than normal," " only 

 normal." In the two exceptional cases the note runs " above 

 normal," and these two notes refer to St. Paul's Island, which, 

 being in Cabot Strait, belongs as much to the Atlantic as to 

 the Gulf. 



The lack of connection here noted seems a point of such 

 importance that I will illustrate it by another example. Pictou 

 on the Gulf and Halifax on the Atlantic are on opposite sides 

 of Nova Scotia and only about 100 miles apart, a much shorter 

 distance than separates St. John and Halifax. The large tide 

 gauge at Pictou was only maintained during the summer of 

 1896. I have compared the records from it with those from 

 Halifax. In the following from my note-book the first note 

 refers to Pictou, the second to Halifax : — July 3, " marked " 

 — " normal " ; July 17, " nothing " — " strong " ; July 25, 

 "nothing" — "strong"; Sept. 19, "nothing whatever" — 

 "strong"; Sept. 20, " feeble "—" strong " ; Sept. 24, "weak" 

 " strong " ; Sept. 28, " strong "— " normal " ; Nov. 1, " feeble " 

 — " strong " ; Nov. 11, "• nothing " — " strong " ; Nov. 14, " noth- 

 ing" — "strong." These were, I believe, the only cases in 

 which the undulations at either place were decidedly above 

 normal and therefore suitable for founding such a comparison 

 on. Thus there is no correspondence between the occurrences 

 of secondary undulation at Halifax and Pictou. 



Now, according to the theory of atmospheric billows, two 

 points so comparatively close together as Halifax and Pictou 

 should show a close correspondence of times of strong undula- 

 tions ; for it cannot be conceived that " atmospheric waves of 

 from 15 to 30 kilometers long " whose " average velocity is 60 

 miles per hour in summer"* could raise strong secondary 

 * DeDison, Proc. Can. Inst, Jan. 16, 1897, p. 30; Feb. 6, 1897, p. 58. 



