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Page:Popular Science Monthly Volume 23.djvu/533

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DISTRIBUTION OF NORTH AMERICAN FORESTS.

The difference of time is so great that the smaller relative surface is insufficient to compensate for the evaporation that must occur if the grilling principle, or the pure and simple action of radiant heat, were only made available, as in the above ideal roasting of the small joint.

What, then, is added to this? How is the desiccating difficulty overcome in the large-scale roasting? Simply by basting.

All night long and all the next morning men were continuously at work pouring melted fat over the surface of the slowly-rotating carcass of the Warwick ox, skillfully directing a ladleful to any part that indicated undue dryness.

By this device the meat is more or less completely enveloped in a varnish of hot melted fat, which assisted in the communication of heat while it checked the evaporation of the juices. In such roasting the heat is partially communicated by convection through the medium of a fat-bath, as in stewing it is all supplied by a water-bath.

I purpose making an experiment, whereby this principle will be fully carried out. I shall melt a sufficient quantity of mutton-fat to form a bath, in which a small joint of mutton may be immersed, or of beef-fat for beef; and then keep the melted fat at about the cooking temperature, or a little above it—say the boiling-point of water, which will be indicated by the spluttering due to the evaporation of the water in the meat. The result of this experiment will be duly reported to the readers of "Knowledge" when I reach the general subject of frying. In my next I must continue this subject of roasting, which is by no means exhausted yet. Count Rumford devotes seventy pages to it, and I quote his words for my own use. He says: "I shall, no doubt, be criticised by many for dwelling so long on a subject which to them will appear low, vulgar, and trifling; but I must not be deterred by fastidious criticisms from doing all I can do to succeed in what I have undertaken. Were I to treat my subject superficially, my writing would be of no use to anybody, and my labor would be lost; but by investigating it thoroughly I may, perhaps, engage others to pay that attention to it which, from its importance, it deserves."[1]Knowledge.

 

THE GEOLOGICAL DISTRIBUTION OF NORTH AMERICAN FORESTS.
By THOMAS J. HOWELL.

THE causes which have determined the present distribution of the flora of the world have occupied the minds of some of the ablest students of natural history, but no satisfactory solution of the problem has yet appeared. If we accept the theory of Raumer, that plants are

  1. "Essays Political, Economical, and Philosophical," vol. iii, p. 129.