N.--As to the sorts of grass, I have to observe generally, that in proportion as the colour of the grass is _deep_; that is to say, getting further from the _yellow_, and nearer to the _blue_, it is of a deep and _dead yellow_ when it becomes straw. Those kinds of grass are best which are, in point of colour, nearest to that of wheat, which is a fresh pale green. Another thing is, the quality of the straw as to _pliancy_ and _toughness_. Experience must be our guide here. I had not time to make a large collection of sorts; but those which I have sent to you contain three sorts which are proved to be good. In my letter of the 3d instant I sent you _sixteen_ pieces of plat and _eight_ bunches of straw, having the seed heads on, in order to show the sorts of grass. The sixteenth piece of plat was American. The first piece was from _wheat_ cut and bleached by me; the rest from _grass_ cut and bleached by me. I will here, for fear of mistake, give a list of the names of the several sorts of grass, the straw of which was sent with my letter of the 3d instant, referring to the numbers, as placed on the plat and on the bunches of straw.
PIECES BUNCHES SORTS OF PLAT. OF STRAW. OF GRASS.
2.} { Melica Cærulea; or, Purple Melica 3.} 2 and 3 { Grass.
4.} { Agrostis Stolonifera; or, Fiorin Grass; 12.} 4 and 12 { that is to say, one sort of Couch-grass.
5.} 10.} 5 and 10 Lolium Perenne; or Ray-grass.
6.} { Avena Flavescens; or, Yellow Oat 11.} 6 and 11 { grass.
7.} { Cynosurus Cristatus; or Crested 15.} 7 and 15 { Dog's-tail grass.
8.} { Anthoxanthum Odoratum; or, Sweet 13.} 8 and 13 { scented Vernal grass.
9.} { Agrostis Canina; or, Brown Bent 14.} 9 and 14 { grass.
O.--These names are those given at the Botanical Garden _at Kew_. But the same English names are not in the country given to these sorts of grass. The _Fiorin grass_, the _Yellow Oat-grass_, and the _Brown-Bent_, are all called _couch-grass_; except that the latter is, in Sussex, called _Red Robin_. It is the native grass of the _plains_ of Long Island; and they call it _Red Top_. The _Ray-grass_ is the common field grass, which is, all over the kingdom, sown with clover. The farmers, in a great part of the kingdom, call it _Bent_, or _Bennett_, grass; and sometimes it is galled _Darnel-grass_. The _Crested Dog's-tail_ goes, in Sussex, by the name of _Hendonbent_; for what reason I know not. The _sweet-scented Vernal-grass_ I have never, amongst the farmers, heard any name for. Miss WOODHOUSE'S grass appears, from the _plants_ that I saw in the Adelphi, to be one of the sorts of Couch-grass. Indeed, I am sure that it is a Couch-grass, if the plants I there saw came from her seed. My son, who went into Connecticut, who saw the grass growing, and who sent me home a specimen of it, is now in England: he was with me when I cut the grass in Sussex; and he says that Miss WOODHOUSE'S was a Couch-grass. However, it is impossible to look at the specimens of straw and of plat which I have sent you, without being convinced that there is no want of the raw material in England. I was, after my first hearing of the subject, very soon convinced that the grass grew in England; but I had great doubts as to the capacity of our _sun_. Those doubts my own experiments have completely removed; but then I was not aware of the great effect of the _scalding_, of which, by the way, Miss WOODHOUSE had said nothing, and the knowledge of which we owe entirely to my son James' journey into Connecticut.