XiV Prefaee. 
I had intended to form, from my own expe- 
rience, assisted by the materials I could obtain 
from others, an essay, in which all the knowledge 
we have of the agricultural uses of the gypsum 
might be concisely promulgated. But, on a subject 
in which practice is the surest guide, facts, vouch- 
ed by men of practical knowledge exhibited in 
their own words, seemed to me best calculated to 
promote truth, remove prejudice, and to excite 
and encourage inquiry and exertion. 
I had answered the queries on this subject 
for private information, chiefly from the know- 
ledge I had gained, in a long course of practical 
attention to the uses and effects of the gyps; and 
I find, since receiving the communications from 
my friends, that their experience and mine, in 
general, agrees. 
As to opinions and conjectures though they 
may not at first be solid, they may possibly lead to 
farther discoveries. In statements of agricultural 
facts, made to those who are to judge of the merit 
of experiments or practice, it is perhaps right to 
avoid opinions and speculations. But in the pre- 
sent publication, I have thought it proper to throw 
out opinions, and even slight conjectures. My 
view is to draw forth better opinions, and to set 
scientific men to thinking on the subject. 
