The value of the various calculations that statisticians indulge in is largely discounted by the fact that allowance is rarely made for changing conditions. Such has been the ratio, such is the ratio, and therefore in so many years' time such will be the ratio, is the burden of their calculations, so that while their figures for the past and present may be both correct and instructive, their calculations for the future are frequently of little practical utility; and it is this failure to allow for any variation in conditions that renders Mr. Davis's figures of so little value, and Sir W. Crookes's conclusions, which are based on them, of no greater importance. It is surprising to find how much value Sir W. Crookes attaches to Mr. Davis's figures, and it leads one to the conclusion that he has either not examined them very closely, or shares with Mr. Davis a fondness for "purely speculative computations"; and while it is not seemly to accuse, as has been done, a man of Sir W. Crookes's standing and reputation of resorting to "bucket-shop" methods to support his conclusions, it is difficult to avoid thinking that the anxiety to establish those conclusions has not only led him to accept Mr. Davis's calculations without proper examination, but has also influenced the preparation of some of his antecedent data and led him to subordinate facts as a means to a required end. Since Sir W. Crookes thinks so highly of Mr. Davis's figures and upon them has based some of the most important conclusions of his address, and as Mr. Davis himself is so ready to find fault with the calculations of others, it might be well just here to see how some of Mr. Davis's own calculations have been verified and what amount of dependence should be placed upon his figures or on deductions from them.