Lesley.] 



120 



Oct. 18, 



Beds 1— 50 

 « 51 — 100 

 " 100 — 115 



115 



Grand average 

 of 115 beds. . . 



4129.80 4081.00 

 3908.40 4015.30 

 1236.90 1179.30 



066.55 690.35 194.80 211.25 

 779.50 708.10 283.60 260.70 

 198.90 220.40 | 53.70 80.30 



9275.10 9275.60 



80.655% 80.668% 



1644.95 1624.85 



532.10 552.25 



14.30% 14.13% 4.627% 4.802% 



To show how worthless small groups are for analytical purposes it is 

 only necessary to combine the top and bottom specimens of ten beds, and 

 notice the absence of any marked regularity, thus: 



Table 3. 



Beds 1 to 10 L. C. 82.40 M. C. 13.33 I. M. 3.98 



Beds 11 to 20 83.25 9.57 2.03 



Beds 21 to 30 79.69 14.50 5.57 



Beds 31 to 40 80.63 14.11 4.66 



Beds 41 to 50 79.55 16.32 4.06 



but, on the other hand when grand averages of fifty beds are taken, a pic- 

 ture is obtained of the pretty uniform distribution of the two carbonates 

 throughout at least this part of the formation, thus : 



Table 4. 



Average of 100 specimens (taken from top and bottom*) of fifty beds. 



Beds 1 to 50.... 82.15 13.57 4.11 



Beds 51 to 100.... 79.54 14.87 5.44 



Beds 101 to 113.... 79.54 14.17 4.47 



Beds 1 to 115.... 80.662 14.215 4.715 



I shall now give a specimen of the results to be obtained by grouping 

 the low magnesian beds together and the high magnesian beds together and 

 for the present leave the discussion of the data presented above to others. 



I select 14 limestone (A) beds alternating, with singular regularity, with 

 15 magnesian beds (B, distinguished by black-letter) viz. : beds 87, 88, 89, 

 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 103, 106, 

 107, 108, 109, 110, 111, 112, 113, 114, 115 ; and the result is as follows : 



Lime Carbonate. 

 Bottom* Top.* 



96.62 93.47 



63.83 63.00 



Table 5. 



Magnesian Carb. 

 Bottom. Top. 



1.97 2.58 



27.93 28.52 



Insol. Matter. 

 Bottom. Top. 



1.24 3.57 



7.25 7.24 



(A) 

 (B) 



Of the 164 percentages here represented, five are abnormal, as may be 

 noticed by consulting the last part of Table 1. These are included, how- 

 ever, in Table 5. If we combine all the bottom and top analyses of Table 

 5, without excepting any, we get the following general average : — 



* Not of the bed, but of the R.R. cutting. 



