Page:Popular Science Monthly Volume 6.djvu/783

Rh the Rocky mountains were almost the ultima Thule of Western adventure. The same region now is wellnigh the geographical centre of the West, and has been the field of much good work by naturalists. However, that insect, although most assiduously looked for, was never found, and belief had nearly settled down that Say was in error about his new species, or that the species had become extinct. Unfortunately, Say's collections were all long ago destroyed, and only his published description of the species remained.

In the current number of Psyche, E. P. Austin says: "Last summer, while engaged on the survey of the north boundary of Nebraska, I visited one of the numerous hills of drifting sands with which a large part of that section is covered, when I saw a cicindela fly up, which was evidently quite different from any thing I had ever seen before; on following it, it lighted on a steep slope of bare sand, where, after some exertion, I succeeded in capturing it. By going over the sand, I saw others, and during the time that I remained in that vicinity—about an hour—they increased in frequency, a circumstance which I thought due to disturbing them in their hiding-places by trampling the sand."

On his return East, Austin worked the insect out; and lo! it was the long-lost species, Cicindela limbata of Say.

The rediscoverer says: "It may appear singular that the species should have remained undetected so long; but owing to its small size and great activity, as well as because it probably is confined to the barren sand-hills, which are not promising regions to collect in, it is evident that, but for its accidental discovery, it might have remained undetected much longer."

Economizing the Heat of Waste Steam.—Mr. Spence lately exhibited in London his plan for the employment of waste steam as a substitute for fuel. This method is founded on a discovery made by the father of the inventor, and announced by him to the British Association in 1869, viz., that steam liberated at atmospheric pressure, and passed into a saline solution having a boiling temperature higher than that of water, raises the solution to its own boiling-point. Thus, as Mr. Spence showed experimentally, if we take a nitrate-of-soda solution, which boils at 250°, and blow into it steam at 212°, the temperature of the solution will be raised to 250°, the steam condensing and yielding its heat. Mr. Spence uses the solution of caustic soda, both on account of its high boiling-point, and because it does not act injuriously upon iron. The exhaust steam will raise this solution to a temperature of 375°, and the heated solution is then circulated through pipes in an ordinary boiler, and its heat is radiated, for the purpose of generating steam in the place of heat derived from fresh fuel. If the boiler is at a pressure of 30 pounds, the solution will leave it at a temperature of 250°, so that 125 degrees of heat would have been yielded to the water. The solution having been to some extent diluted by the condensation of the exhaust steam, its capacity for heat will be correspondingly reduced; and, if steam at 212° were again blown through it, it would not reach the same temperature as before. It is therefore passed into another boiler of ordinary construction, where it takes the place of water, and is concentrated by steam being generated from it; and in this way its capacity for receiving heat is restored.

Mr. Spence maintained that, if, by taking advantage of his father's discovery, a mode of utilizing the large amount of latent heat contained in the steam now thrown into the atmosphere could be brought into practical operation, so that this latent heat could be made to do actual work, the discovery would be one of enormous value, and he announced his intention of speedily trying the experiment on a manufacturing scale.

Reproduction of Burnt Records.—M. Rathelot, an officer of the Paris law-courts, has succeeded, in an ingenious manner, in transcribing a number of the registers which were burnt during the Commune. These registers had remained so long in the fire that each of them seemed to have become an homogeneous block, more like a slab of charcoal than any thing else, and, when an attempt was made to detach a leaf, it fell away into powder. Many scientific men had examined these unpromising black