134 New Work on the History of the Art of 
that it belongs to the right square, the right rectangular, or to the 
doubly oblique, prism ; but the probability is that it would be neces- 
sary to effect its determination through the 3d class. ; 
To the inquiry how many characters may be considered as es- 
sential? (by which I suppose the question is asked how many of the 
natural properties are available as characters) I reply that structure, 
specific gravity, hardness and lustre, afford essential characters of 
full and perfect sufficiency for the distinction of classes, orders, gen- 
era and species, provided these groups are framed in accordance 
with the principles of Natural History. 
Cuarves U. Sueparp. 
New Haven, Aug. 9, 1836. 
Arr. X.—M. Alexandre Brongniart’s New Work on the History 
of the Art of Pottery and of Vitrification. 
Museum to illustrate this subject. 
In a letter to the editor, dated March 8th, 1836, M. Brongniart 
remarks: “1am much occupied with a work upon the history of 
the plastic art, or the art of pottery; and the requests which I take 
the liberty to annex, have for their object the enriching of a grand 
and instructive collection which I have formed at Sévres, of every 
thing relative to the art of pottery, and consequently to the perfec- 
tion of the work which I have undertaken, and of which | have pub- 
lished the plan in an extract from the article Pottery, in the Dic- 
tionary of Technology published at Paris. It forms the half of a 
volume, i in which I have endeavored to present the principles of the 
art in a manner at once practical, philosophical and elementary. I 
am this year about taking a journey to England and to Germany, 
for the purpose of collecting pemcn and specimens for this work 
and for the collection at Sévres. 
As this undertaking of M. Beohguian:i is important and interesting 
to science, to history, and to the highly useful and beautiful art of 
pottery, we publish a translation of the exposé entire, and strongly | 
recommend it to the attention of all those who, in this country, have 
it in their power to promote the object in view. It is quite super~ 
fluous to add, that M. Brongniart’s character furnishes every secu- 
rity for the able and faithful performance of the duty which he has 
undertaken.— Ed. 
