ON DEPOSITIONS OF MUD IN THE TAY. 
5 
soil is composed, comes to be precipitated from the waters of the river which held 
it in suspension. It is not necessary here to detail the methods pursued to 
accelerate the process of deposition and accumulation, or to notice the plans of 
embankment for defence or inclosure, or the modes of improving the value of 
the land recovered, farther than to state generally that the first part of the 
process consists in running out strong stone breakwaters, which occasion eddies 
or partial stagnations in the current, and then, when accumulations of mud have 
been obtained by the shelter of these, to plant Bullrushes, so as to obtain a more 
speedy enlargement and rapid accumulation of the earthy particles desired to be 
retained. Under these circumstances, one would naturally suppose that the 
chief periods of accumulation should be at seasons of biennial floods, and that 
during the spring and autumn freshes, when the Tay comes rolling down from 
the mountains, charged and rendered turbid with mud, then the largest de¬ 
posits should occur; and again, that the periods most favourable for diurnal 
deposit would be when temporary stagnation in the waters of the rivers takes 
place at the turn of the tide, when precipitation would most readily occur if 
the waters were left in a state of temporary repose. Having mentioned these 
as my conclusions from theory, I was surprised to learn that they were the reverse 
of facts, and that, so far from the deposition of silt being most abundant when 
the river carried along with it the greatest quantity of earthy matter, then it was 
that no deposit, whatever took place, the period of flood being that in which, 
instead of accumulation ‘being obtained, much that had previously taken place 
was apt to be swept away. As to the bi-diurnal tidal deposit, my opinions were 
equally unsupported by fact; as low water approached, no precipitation whatever 
was perceptible; nor, generally speaking, could any be observed after the tide 
had begun to recede. The most favourable seasons for deposit were those in 
which the river was moderately full and clear, without turbidity or flood; and 
the best time of the day was just after the turn of and during the rising tide. 
So strikingly anomalous did these statements appear to be, that, though made by 
one of the most experienced, observant, and intelligent farmers, who had long 
been engaged in embanking, I somewhat doubted his accuracy, until, after a 
most minute and laborious inquiry, I had them corroborated in every parti¬ 
cular by all who had had any opportunity of observing the matter. So greatly, 
in reality, had the farmers been struck with the fact, that a general belief 
obtained that no deposit whatever was obtained directly from the waters of the 
river; and that the mud which had accumulated from four to eight feet thick 
within the last twenty years, over hundreds of acres of land, now in cultivation, 
was wholly an oceanic production. The following, among other facts, evolved 
themselves in the course of these inquiries. 
Shortly after the turn of tide, when the current of ebb begins to set outward, 
