24 KOYAL SOCIETY OF CANADA 



At St. Paul Islaiui, some mnounl of secondary undulation is more 

 usually present than absent ; but it seldom attains a range of more than 

 two or three inches. At the date in question, they have very much their 

 usual character. 



The secondary undulations shown in the Uvjcompanying plate, are most 

 pronounceil at Yai'inoulh, where they attained a range of over four feet 

 on Januar}' 1. A moderate amount of secondary undulation almo.st 

 constantly occurs at that station, and it is frequently pronounced. 



At St. John, X. H.. undulations of nearly half a foot occur occasion- 

 ally ; and some amount of secondary undulation is perceptible at perhaps 

 one-half of all the tides there registered, although it is usually feeble. 



The.se notes are given to explain in a general way what is usually 

 observed at these tidal stations, with regard to secondar}- undulations in 

 the tide ; so that the illustrations now'given may be better understood. 

 The following list gives the maximum ranges which occurred at these 

 stations at the date referred to, and the range of the tide itself at the 

 time. The range of the secondary undulations is measured from the 

 mean tide line running centrally through them, in order to eliminate the 

 general rise and fall of the tide from the result. The relative periods of 

 the undulations need not be detailed, as these are evident in the plate 

 .itsel f. 



Becondary tidal undulations of Jan. 1, 1890. Time of occurrence, 



range, etc. 



Halifax. At Low Water, Jan. 1, from 2^ 30"" to 5'' 30™ ; and at the 

 following High Water, from 8'' 00'" to 10'' 00"^. 

 Maximum range of secondary undulations, 120 and ri5 feet. 

 Range of the tide itself at the time, 3*60 feet. 

 The undulations have thus 33 per cent of the range of the tide. 



St. Paul Island. Near High and Low Water, Jan. 1 and 2. 

 Maximum range of secondary undulations, 0*23 of a foot. 

 Kungo of the tide itself at the time, 2-20 feet. 

 The undulations have thus 10 per cent of the range of the tide. 



Yarmouth. At Low Water, Jan. 1, from 6'' 00" to fc'' 30'". 

 Maximum range of secondary undulations, 420 to 4*70 feet. 

 Range of the tide itself at the time, 10-40 feet. 

 Tlie undulations have thus 45 per cent of the range of the tide. 



St. John, N. B. At Low Water, Jan. 1, from G"* 30'" to 9'' 00'". 

 Maximum range of secondary undulations, 1*90 feet. 

 lîango of the tide itself at the time, 18*00 feet. 

 The undulations have thus onl}' 11 per cent of the range of the tide. 



The undulations are naturally most consiMCuous on the tide (races at 

 Li a es of high aiul low water ; but in the case of undulations of such 



