14G 
On Modes of Comparing the 
specific gravity, but the size and shape of each "rain materially 
influences the quantity contained in the bushel— a source of in- 
accuracy which would be avoided by weighing in water. 
In touching on the relative degrees of nourishment of different 
vegetables, I may advert to another point which seldom receives 
the attention it ought — I mean the quantity of nourishment per 
acre afforded by different crops. When we speak of so many 
tons per acre of potatoes, mangold -wurzel, or swedes, or so many 
bushels of barley and oats, we rarely calculate the number of 
pounds of beef or mutton which they should respectively pi'oduce. 
Von Thaer has given us the following table of equivalents 
which afforded equal nourishment to animals, taking 100 lbs. of 
ordinary hay as the standard : — 
Equivalents, 
lbs. 
Wheat 27 
Barley . 
Maize . 
Beans 
Clover (red) 
Hay (ordinary 
Potatoes 
Beet 
Wheat-straw 
54 
59 
83 
90 
100 
200 
397 
400 
Professor Johnston, in his excellent little work on agricul- 
tural chemistry, has extended the above table considerably, as 
follows : — 
Hay 
Clover hay 
Green clover 
Wheat-slraw 
Barley-straw 
Oat-straw 
Pea-straw 
Potatoes 
Old potatoes 
Carrots . 
Turnips 
Cabbage 
Peas and beans 
Wheat . 
Barley 
Oats 
Indian corn 
Oil-cake . 
lbs. 
10 
8 to 10 
45 to 50 
40 to 50 
20 to 40 
20 to 40 
10 to 13 
20 
40 
25 to .30 
50 
20 to 30 
3 to 5 
5 to G 
5 '.0 6 
4 to 7 
5 
2 to 4 
weight or measure can never be as true a criterion as the specific gravity 
measured by an instrument. — W. H. H. 
