106 - ANNUAL REPORT 
The accompanying cuts illustrate this method of prospecting; the 
section shows the presence of soil, soft clay, soft red shale and hard blue 
shale. 
Assuming that analysis has shown the soft red shale to be the most 
suitable and finding an average depth of 20 feet of this material, we 
evidently have available in each square of 50 feet, 50x50 20=50,000 
cubic feet of clay. But this procedure has not only shown the amount of » 
clay available, but also the variations in composition, since two samples 
are taken from a depth of 20 feet. ‘This point should be well considered, 
as a knowledge of the composition of clays not only gives the prospective 
manufacturer accurate and valuable data, but is also of great help when 
manufacturing has been begun, since it tells the chemist what to expect 
in the future and may prevent some costly mistakes. When .this is duly 
weighed, it surely ought to remove the last prejudice against the expendi- 
ture of the money necessary to carry on the preliminary survey. 
METHOD OF DRILLING IN CLAY DEPOSITS. 
In the prospecting of clay property, the samples required can be 
obtained either by digging down through the strata to be examined or 
by drilling holes. It is evident, of course, that by digging prospecting 
holes, the samples obtained will be large in amount and permit of 
sampling the deposit in the most thorough manner, and ultimately this 
must be done in every clay deposit even though only in, say, half a dozen 
places, at the extremities of the land available and in equal intervals 
between them. However, the cost of digging the holes is not incon- 
siderable: and would not be resorted to until one is quite sure of his 
ground. Drilling, being so much cheaper, should be carried on during 
the preliminary survey, and it may be done as follows: 
1. Boring with an auger. Applicable to clays which are free from 
stones and the softer grades of shales. 
2. Drilling with the churn drill. 
3. Combination of churn drill and auger. 
4. Core drilling, with a serrated pipe, applicable to rather soft ma- 
terial only. 
5. Core drilling with a pipe with sharpened edge at bottom, driven 
down. 
6. Combination of churn drill and pipe drill. 
7. Marl sampler, used in quite soft materials. 
Auger. —The auger is the most successful implement in the exploit- 
ing of clay and shales and should be used much more extensively than 
it is. A good two-inch auger of best quality will answer in many cases. 
Catlett* describes an auger which he has used in his prospecting 
work and which has given good service. The bit is made of steel or 
*“Trans. Am, Inst. Mining Eng., 1897. 
