438 REPORT—1899. 
photographic picture can be reduced to the corresponding real values in 
the same general manner. These are the diameters of the body and of the 
limbs, the length of the body, and the distances between any points of 
reference that may have been marked in the way described above, as seen 
in projection against the medium plane of the body. 
Verification of the Results:—Numerous experiments have been made to 
test the exactitude of this photographic method of measuring living animals. 
The results of those made at the Show of the Royal Commission on Horse- 
breeding are given in the Appendix to the Blue Book. They are summarised 
as follows :—Two advanced veterinary students were deputed from the 
Royal Veterinary College to assist one another in measuring the animals 
that were photographed, for the purpose of controlling the photographic 
calculations. Each horse had its height above the ground measured at 
the withers, at the hollow of the back, and at the croup. Comparisons 
happened to be available in only twenty-six out of the twenty-nine 
premium horses, one of the latter having not been photographed, and two 
out of the remaining twenty-eight having been overlooked by the 
measurers. The comparison came out as follows :— 
Sums of the Differences between Calculated and Observed Values. 
Inches 
No. of Cases Heights at 
_ | +f Totals 
26 Withers . . i een Fy eee 208 
26 NIB eek 5. omens 15 | 8t 232 
26 Croup Rae 8 | 12 | 204 
78 | Totals ae 303 34 | 642 
The approximate equality between the totals of the — and + differences, 
which are 30} and 34 respectively, testifies to the average correctness of 
the method and of the work. That between the summed results for the 
withers, back, and croup respectively, which are 203, 234, and 201, shows 
that each of these has been determined with about the same degree of 
correctness. It is therefore justifiable to treat all the 78 events on equal 
terms, in order to ascertain what that degree really is. This is done in 
the following table :— 
Distribution of the Seventy-eight Differences without regard to their — or 
+ signs. 
Iatneheaine Difference ve Sums from beginning 
to nearest 3 inch o. of Cases i.) ot; ne 
Totals Per cents. 
0 10 10 13 
z 11 21 27 
a 20 41 52 
E: 9 | 50 64 
1 8 58 | 74 
14 4 32 7) 
15 5 67 86 
13 4 71 91 
2 6 77 99 
2h 1 78 100 
— 
