bone after the latter came to be of considerable commercial importance; for sperm oil too it is unmistakable.
The most remarkable drop is that for whale oil and whale bone in 1852. Doubtless, this is in part due to unfavorable years, but it is probably also an after-effect of the reduction of the fleet seen in 1850 and 1851—a reduction the effects of which would not be seen until at least a year or two later, when the vessels would be returning with their cargoes.
Diagram 2. Whale Oil, Brought in by American Fleet. Unit for ordinates = 20,000 barrels.
That the depression does not affect the sperm-oil curve is perhaps due to the fact that the sperm whales might be taken at any part of the voyage—not merely on closely circumscribed "grounds" during a limited "season."
The curves for whale oil and sperm oil differ in certain important points. Except on the "tails" of the curves the imports of the more valuable sperm oil are far in defect of those for whale oil. Probably in consequence of the greater demand the source was earlier exhausted. The mode of the sperm-oil curve lies, in consequence, nearer the inception of the industry, and the curve is therefore far more skew. It is interesting to note that in more recent years, the imports of sperm oil have been maintained at a relatively higher point than has that of whale oil. It is quite outside my present purpose to discuss the reasons for this.
For many years, bone was of very little commercial importance. The entries for bone lie close to the base line up until about 1830, after which the imports are on a rising curve until the decade 1845-1855, after which
