FORMATION OF THE SOCIETY : UNPUBLISHED RECORDS. 15 
not be useful if yourself and Messrs. Briggs, Morton, and Holt 
were to compare notes together. If you think so, I should name 
it to them, and arrange for the meeting immediately after we 
have transacted our ordinary business the next time the council 
meets. I could arrange the meeting so as to suit the convenience 
of all parties. 
I am, dear Sir, yours truly, 
Thomas Wilson. 
A day or two afterwards, Mr. Embleton received a letter from 
Prof. Johnston which is printed below, asking for various items of in- 
formation respecting the Yorkshire coal-field. He was desirous to 
make his lecture as widely interesting as possible before it was 
printed. 
Prof. Johnston to Mr. Embleton. 
Durham, 18th Jane, 1838. 
My Dear Sir, 
If I could have met you yesterday afternoon in Leeds I should 
have saved you the trouble of reading this letter ; though the greater 
of writing to me, I should still have been anxious to impose upon 
you. I should like to notice in my lecture, when it is printed, 
the subject of the structure of coal, which I have marked in my 
notes to be alluded to, but with some other things find I have passed 
over. Would you favour me with the result of your observation in 
regard to the Gleet of the coal. 
1st. — If it is always parallel to the water level, and at right 
angles to the dip. 
2nd. — If it is uniform in direction in the same seams, the dip 
being constant, and if it vary with the dip. 
3rd. — If it be parallel to the same line or run in tlie same di- 
rection, (a) In the diff'erent coal seams worked in the same pit. 
(b) In the different layers of the same seam. 
4th. — In respect to the dip the coal may be expected to undulate 
now and then, so that the dip shall slightly vary in different parts of 
the same seam, but in different seams lying over each other does the 
general dip always correspond, or does the dip of (a) differ from that of 
(b) either in intensity, (number of degrees), or in direction. If the 
