On the Phosphoric Strata of the Chalk Formation. 73 
The large hard fossils are first broken with stone-hammers, in 
a similar way to that in which gravel is prepared for road-making, 
and then reduced to powder by the mill ; they, however, require 
to be passed through the rollers two or three times. 
In any of the above states the prepared marl is fit to be applied 
to the land by the drill, or to mix with ammoniacal manures.* 
The mill is attached to the machinery of a small threshing- 
machine ; it consists of two pairs of cylinders, the upper ones 
being fluted transversely. Scrapers like those used in a common 
bone-mill are indispensable. Two horses will grind up from 2 to 
5 tons a day, according to the hardness of the substance. 
Much trouble and expense would have been saved had the 
marl been dug in the summer months, as it mioht then have been 
dried in the sun before it was housed. The expense of procur- 
ing this marl, when it lies near the surface in tolerable thickness, 
is of course very trifling : the refuse, that is the upper and lower 
portions of the bed not considered worth the trouble of subse- 
quent preparation, if carted away in the gross to be spread from 
the cart upon land requiring phosphatic manure, would pay all 
the expenses. 
It is difficult to estimate the quantity of the phosphoric marl to be 
obtained in the parish of Farnham, but many thousand tons might cer- 
tainly be dug. 
In the adjoining parish of Eentley, which lies west of Farnham, very 
large quantities of a similar des-cription of marl may be procured. In 
the pits which have been examined the fossils are not so numerous as at 
the latter place, but the average composition of the marl, and the cha- 
racter and chemical properties of the fossils, are identical. 
Some of the beds have been evidently worked for agricultural purposes 
at a former period, as is shown by the remains of partially filled-up pits; 
near them also are now lying heaps of the larger fossils, which were then 
rejected as useless. This conclusively proves that the agricultural 
value of this peculiar soil is no novelty, although the cause of its fer- 
tilizing powers was previously unknown. There is evidence indeed 
to show that this selfsame marl, about 60 years ago, was carried into 
Sus>ex as a manure — the distance being upwards of 20 miles. All the 
resident farmers unaiiimously testify to the extraordinary fertility of the 
green band whenever it appears near the surface. 
Analyses of this marl, with a few fossils broken up with it, and of the 
fossils themselves, are here introduced : — 
* The whole class of the green-marl fossils, when nibbed together, or 
ground up in the mill, emit a strong, disagreeable, fetid smell. This is 
a phenomenon dependent upon their chemical composition, which, how- 
ever, it would not be right to discuss here. 
