I have recevd yours of yesterday and thank you for its prompt reply to my inquiries. I did not fully present my general idea, and in doing so partially, with reference to particular points, have a little misled you.

I am now thinking of a basin as extended (above grade 9) as practicable; the shores to vary much in character, sometimes sandy and beach like, [389] sometimes abrupt, sometimes and as much as can be afforded rocky; the bank above also variable, in degree of steepness, and to be, as a rule, overgrown thickly, in a picturesque, natural, completely informal even negligent manner, so that after a few years such slight damages as would occur (with the precautions I have in view) would at worst be inconspicuous. In my inquiry with respect to strictly tidal ground plants I had little reference to the foot of this bank, or to any islands which would bear trees or shrubs.

But I wish to avoid large areas of open water, and also, in order to spread the occasional floods over as much surface as possible and so avoid vertical rise of water to have large flats bearing vegetation which would tend to prevent the formation of waves.

I have large quantities of mud to be dredged and disposed of. I can form flats by making enclosures of solid earth and filling them with mud.

I shall have also large areas of mud and sedge bank already formed, the present surface of which, being several feet above the proposed high water level, must be pared down so that flood water may pass over it.

On these flats I can have a thin layer of any soil I choose and I can allow their surface to vary from a few inches above ordinary high water level to a few inches below ordinary low water level. Thus, as far as practicable, with a rise & fall of but one foot of tide, I can imitate the conditions in which any of the tidal ground plants best flourish. What I chiefly want is to be sure that I can perfectly cover these flats with marshy plants in considerable variety. There are a number of such plants which I know, and which I think could be used by planting sods of them, but upon all these I find myself in doubt as to the most suitable elevation having regard to a tide of one foot. I suppose that the “black grass” wants to be a little above ordinary high water. What I know as sedge (probably different species) grows both above and below this — in sand and in crevices of rocks. Whether it is soil or period of submergence that determines the position I don’t know.

There are many plants with which I have a general familiarity, as making pretty effects on the edges of tidal brackish water, which I fear might not grow where the water is as salt as it will be in the Backbay.

But in general I infer from your letter that without raising the surface of the flats more than a few inches above ordinary high water level I can have a large variety, including in the uppermost possibly certain Solidagos, asters [390] and bullrushes and lower the two or three plants which chiefly cover the marshes between Cambridge and Brighton.