316 Dr Fleming on the Expediency of forming Harbours, ^c. 



at " Tay Bar;" now the total difference in time from the po- 

 sition of Leitli would not reach 39"\ while the distance is 

 about forty miles. This would make the velocity of the tidal- 

 wave from " Tay Bar'' to Leith, compared Avith its velocity 

 from " Tay Bar" to " Dundee," nearly as three to one, and 

 the former more than double its ordinary velocity in the Ger- 

 man Ocean. 



As all the Establishnents of the Ports, in the table, are set 

 down to apparent time, and the actual times of high water when 

 the moon passes the meridian at the same time as the sun, it is 

 probable that, in the reduction, errors may have been introduced 

 rather than corrected, from the state of the data, and that the 

 angular distance of the moon from the sun at the times of obser- 

 vation, may have been overlooked. But some of the anomalies 

 which have been pointed out, in all probability arise from the 

 different standards employed for determining high water, 

 known to be in use. Thus we have the time of high water 

 marked by one observer, when the tide-wave has reached its 

 highest elevation, by another when slack tide occurs, and by a 

 third when the reverse current begins to prevail. There is no- 

 thing, however, in the table to indicate the employment of a 

 common standard. In illustration of the influence which a 

 variable standai'd may exercise on the time of tide, I may re- 

 fer to that excellent hydrographer, Mackenzie, who, in refer- 

 ence to the Pentland Frith, says, " On the shore of Swona, it 

 flows till half-past nine on the east side, and till ten on the 

 west side, on the days of new and full moon. In the middle 

 of the Pentland Frith it is still or slack water, on the change 

 days at half-past eleven, but the tide docs not turn till 

 twelve." 



Now, whatever be the cause of the anomalies thus apparent 

 in the tide-table of the Nautical Almanack, it is surely of im- 

 portance, for the credit of such a national work, that the en- 

 tries which it contains should be accurate and intelligible, or 

 that no tide-table of doubtful character should have a place 

 there. 



I should be soi-ry if these remarks on the charts and tide- 

 table of the east coast of Scotland, even although not re- 

 motely connected with the object in view, led the mind of the 

 reader awny from contemplating the necessity of establishing 



