The Birmingham age-herald., 1911-12-10

| (sound) wave form" is a succession of waves with minute irregularities on the | face of the waves; and thus for the pur- 1 poses of impinging on the ear becomes equivalent to sound of very high pitch. Campbell and Dye have lately published an account of some work on the detection of sounds ordinarily inaudible. Such sounds probably occur in nature, and are produced by various insects. Miall showed
 some years ago that the Harlequin fly re- spends to its mate by a vibratory ap- paratus equivalent to a sound receiver; but the sound is quite beyond human ears. The late Francis Galton once devised a dog whistle of so high pitch that no one could hear it but his dog-a piece of ingenuity which may not be unknown to trainers of learned dogs. But the soundS
 which Campbell and Dye have been in vestigating are those produced by the sound waves of the electric spark. The waves are exceedingly short and often far too high pitched to be audible The ire quencies of these waves were measured in a simple but ingenious way If vibrations are shaken out along a rope one can see the rope arranging itself in wave forms.
 These wave forms are not of the length from crest to crest of the vibrations sent along the rope; they indicate the positions of the movement--the nodes, as they are
 
 waves from their electric spark along a tube in which excessively fine dust was strewn. The travelling waves arranged the dust in little heaps at regular inter vals, thus marking the nodes and enabling the wave length to be ascertained. The in- Vestigators were thus able to measure sounds of a frequency up to S00,000 sec-
 ond Their principal result appeared to show that two sound waves were given, fot o1, all ctric lat nd I, ! the sound waves were double the fre- quency of the electric oscillations. Susceptibility to Tuberculosis A valuable investigation on the suscepti- | blity to tuberculosis at varying ages has | been set on foot in Paris by Drs. Calmette, | Grysez and Letulle In the larger num- Der of cases the tubercle bacillus is ac- | quired in childhood, or in infancy as is
 shown by the greater frequency of posi- | tive reactions to the tuberculine test l among children between the ages of and
 15 In the Presse Medicale the results of | tests applied to 1926 subjects picked at | random from all classes are tabulated. 1 Among 273 infants of less than 1 year whose blood reacted to the suberculine | test one only was less than months | old; the other 24 were between the ages | of months and 1 year. More than % l per cent of the infants examined showed y of a child's life, while it lives relatively | isolated and protected from the contact | of bacilli, it very often escapes con- | zion altogether Contagion begins to l take place when it goes out of doors, es- peeialy when it begins to walk, when its | food is modified, and when it's life and habits are brought more into relation with the surroundings in which it lives. At : years of age more than 90 per cent of children are already contaminated with | the bacillus of tubercle. At 15 years the proportion amounts to 91 per cent, and 1t | oscillates about the region of 90 per cent l til maturity is reached At the age of % | the people who have escaped contagion l altogether are relatively rare. But not withstanding the immense number of peo- pie who are actually infected with the | bacillus only "A per 100 are really tubercu- | ous and become subsequently a prey to | one of the diverse manifestations of tu- | berculosis. Among the majority the in- l lection remains latent or hidden, and I they die from other diseases. pr. Cal | mette, in sumarizing these researches, | calls attention to the necessity of dis | tinguishing between the actual infection | by the bacillus Q'infection bacillaire),
 which is of extremely frequent occur
 renee and may be unaccompanied by any
 morbid symptoms, and tuberculosis which | has characteristic lessons.
 Micr0-O Organism in Bread
 At the Congress of Hygiene, held in | Paris, a discussion took place on the ques- ton of the micro-organisms which might | find place in bread. M Roussel brought l forward some experiments which showed that pathogenic spores could maintain their existence in dough. He was followed l by pr. Balland, who pointed out that | the temperature at which bread was | baked was sufficient to destroy all mi | crobes, even If it were not able to kill all the spores. Dr. Suche of Bordeaux ridiculed both suggestions, and endeavored l to show experimentally that infection by | or from the insides of oaves of baked
 rolls was impossible to the point of im- l possibility. M. Jorisenne of Liege, parti- | san of neither view, drew attention to the l fact that bread could always be sterilized l by the simple expedient of spreading
 it with a thin layer of butter and lightly | toasting It. In a few minutes the hot
 fat, penetrating the interstices sterilizes | the bread.