I837J Suggestions for the Observations of the Tides. 248 



may be induced to make such careful observations as may serve to be 

 compared with the theory. In this hope the present paper is circu- 

 lated. 



The most useful Observations with reference to our general know- 

 ledge of the Tides are the following, beginning with those which are 

 most easily made. 



1. The Observation of the Time of High water at a known place, 

 on any day, and especially at new and full moon. 



2. The Observation of the Time of High water on several days in 

 succession at the same place. 



3. The Observation of the Height of several successive Tides at 

 the same place. 



4. Observations of the comparative Time of High water on the 

 same day at different places in the same seas. 



1. An Observation of the time of High water at a given place on 

 any known day may be useful. 



If the Time of the Moon's southing on the same day be noted, this 

 will facilitate the use of the observation, and will furnish an additional 

 evidence of the correctness of the date. 



The Time of High water on the days of New and Full Moon is 

 more particularly useful than on other days. 



Observations of the Time of High water may be made with suffici- 

 ent accuracy without a tide-post. A place ought to be selected where 

 the water is tolerably smooth. 



2. If there be opportunity at any place, it is desirable to observe 

 the Time of High water every day for a fortnight. 



If it be ascertained that the two Tides on the same day occur at re-, 

 gular intervals, one of them only need be observed. 



But there are often irregularities in the relative Times of the morn- 

 ing and evening Tide ; and these irregularities are different for differ- 

 ent ages of the moon. In this case both daily Tides should be observed. 



3. A single observation of the Height of the Tide is not of much 

 value. But a Series of Heights for a fortnight is valuable, especially 

 if accompanied with observations of the Times. 



The morning and evening Tide are often unequal, and this inequa- 

 lity sometimes varies considerably from one fortnight to another. 



. In Observations of the Height of the Tide, the difference of High 

 and Low water ought to be taken. 



The channel of a river is not a good situation for such Observations. 



4. The usefulness of Tide Observations will be greatly increased 

 if those made at places in the same seas can be compared so as to 

 shew the Rate at which the Tide wave travels ; 



