September 1961
Nerve Cells Talking
?So far we have said nothing about inhibition, even though it occurs throughout the nervous system and is one of the most curious modes of nervous activity. Inhibition takes place when a nerve impulse acts as a brake on the next cell, preventing it from becoming activated by excitatory messages that may be arriving along other channels at the same time. The impulse that travels along an inhibitory axon cannot be distinguished electrically from an impulse traveling in an excitatory axon. But the physicochemical effect that it induces at a synapse must be different in kind. ?Bernhard Katz?
Katz shared the 1970 Nobel Prize for medicine.
September 1911
Tesla Turbine
?It will interest the readers of the Scientific American to know that Nikola Tesla, whose reputation must, naturally, stand upon the contributions he made to electrical engineering when the art was yet in its comparative infancy, is by training and choice a mechanical engineer. For several years past he has devoted much of his attention to improvements in thermo-dynamic conversion, and the result of his theories and practical experiments is to be found in an entirely new form of prime movers. Briefly stated, Tesla?s steam motor consists of a set of flat steel disks mounted on a shaft and rotating within a casing, the steam entering with high velocity at the periphery of the disks, flowing between them in free spiral paths, and finally escaping through an exhaust port at their center. Tesla depends upon the fluid properties of adhesion and viscosity?the attraction of the steam to the faces of the disks?in transmitting the velocity energy of the motive fluid to the plates and the shaft.?
NOTE: The thin steel plates could not with?stand higher temperatures and speeds. Newer materials such as carbon fiber or ceramics may renew interest in this compact design.
Modern Tobacco Ads
?Most people imagine that the wooden Indian has a monopoly of the tobacco sign business, but he has a competitor in the dummy which ostensibly smokes a cigar. The cigar, however, is likewise a dummy, and the smoke comes from a concealed pot of burning tobacco and is intermittently expelled from the lips of the dummy by concealed bellows. One of the most elaborate of these signs is a hollow crescent figure, whose convex face is studded with incandescent lights, and bulbs are also at the outer end of the cigar.?
More mechanical advertising devices are at www.ScientificAmerican.com/sep2011/novelties
Horses and Heat
?The health department of New York city, which has the task of removing dead horses, reported that during the six working days of the hot period of July, 171 horses died each day?a total of 1,026. These horses represented over half a million dollars cash value, which was entirely wiped out in a single week. It is estimated that the money would pay for a sufficient number of electric vehicles to do all of the work done by the horses, and do it more efficiently and economically.?
September 1861
Cocaine Isolated
?The German chemist, Dr. Niemann, has recently been making experiments with coca leaves, and has obtained from them an alkaloid which he proposes to call cocaina. Pure cocaina is colorless; the crystals are large prisms. It has an alkaline reaction, a bitter taste, and when placed upon the tongue it promotes the flow of saliva and induces a sensation of cold. Several German chemists and physicians have recommended coca leaves as a substitute for coffee in European armies, on account of the well known qualities of coca, to preserve life and strength for a considerable time without common food.?
Nautical Discipline
?The British merchant ship Star of the East, while on her passage from Bombay for Liverpool, was lost while beating through the Mozambique channel. At the official inquiry into her loss, the first witness was the sailmaker of the ship, who stated that when she struck she was about a mile off the shore. Whereupon Mr. Tyndall, the attorney for the government Board of Trade, says to him, ?Didn?t you think it strange that the ship should be so close in shore?? Witness??We?re not allowed to think; there?s only the cook and the captain allowed to think on board a ship.? The answer was a sockdologer, and the representative of their lordships, after this brief exposition of sea law, made no more interruptions.?
Source: http://rss.sciam.com/click.phdo?i=e5ece38ef29ba7f8b8d5b5c1776d04db
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