Just How You Get Your Sense of Touch Tips Enables the Experimentér to Determ 5 Shown by the Shaded Areas. the Lined Portions and the Mounted on a Wooden Handle in Amount of Pressure Necessarily App Determining the Amount of Pressure Produced 8 Delicate Balance. The Hair Bends and the lied by the Hair. FIG. 5--A Draftsman's Com- ine the Distance Between the Points Necessary to Produce the Sensation of Discrimination. . equation anc the thickness of the skin aff delicacy of touch to some extent, and so size, the weight, and the roughness of surface (the object felt. Ordingrily, with small ob "up to a pound or so in weight and a few in screpancy of a thousandth {inch will be readily detected. Under proper { eumstances, however, it is possible to (figure. When the surfaces are pol tsmall size, as with small steel balls, the "will notice differences of a hundred-thoussndth 'of an inch. te A method of demonstrating sengitiveness of touch is explained in r Science Monthly by C. A. Briggs, who 8 machinist-microm- stor aod a thin aluminum handle, in which | Steul ball is sot at each end, as shown in one | the secompanying iDustrations. In a | micrometer the faces on the spindle and [vil are flat and perpendicular to the axis k with an accuracy of between dth and one-ome hundred-thousand inch. With a micrometer that Is condition 2 possible to adjust m probe will just be held in perceive } Are numerous and varied, such qualities of sensation relating of discrimina the sense of pain. eareful investigation of the skin surface bears (out the idea that these three great classes of Qutaneous (skin) sensations have special mechan- {sms or classes of mechanisms for each individual ¥ & 3 isi i 3d FFs fps 2 se §f i © In considering these senses, it is best to take them up and deal with each separately. Through the agency of the skin and the touch-corpuseles, Jou are able to perceive various qualities such as #hape, texture and hardness of the objects in gontact with the skin. Of course, the sense of ] also has associated with it a musculsr following very simple H. Kraus describes in skin is pushed downward or pulled instrument. A sense 2 Jrnenure is announced to the bras Bei- t on the tongue and nose, & pres- two grams per square millimeter to the brain that a certain region hed. On the back of the forearm it requires a GETTING the MO ILK is one of man's most valuable féods. The baby, while he lives on mother's milk, : is almost free from putrefactive bacteria 'his intestine. Later, on a mixed diet, he aceu- plates a choice lot of bacterial enemies--un. '#rendly germs--and they colonize his intestine for the rest of his life. . Sour milk was lauded by Metehnikoff and hers as a sort of elixir of life. It was thought it the bulgarian bacillus and the lactic acid t it formed, transformed the bacterial popula- hn of the intestine and exsluded undesirable Ee Sa phos tv assepted ag 4 d scienti 2 18 a whole- food and it helps to keep the intestine Ba sweet milk, and it m ul which the real friendly germ of the tin 4 bacillus acidophilus, feeds. ~ You can plant the bacillus acidophilus in the \ by feeliug cultures of it, and germs of ) type that are always present in a certain Ber will multiply if a diet rich in milk sugar It was thought by Metchnikoff that the \ could be implanted and culti- gd in the intestine, but later experiments indicate. that this is not so, and that he the bacillus acidophilus with the bacillus " The practice of eating the culture of bacillus bulgaricus would seem, there- be of no practical benefit and the results were sought to be obtained by this method be obtained by drinking libe th quanthios of , and the use of milk sugar in | is rather expensive, but if it does added well worth a trial, and on present evidence it be good for the a individual to try his intestinal condition by sah methoy are by the "best families" of germs. A mix- made by adding several ounces of sugar of pllk to a quart of sweet milk is fattening and ishing, not only to the body but to the friend. ST Out of MILK ly germs of the intestine. People who cannot take Sweet milk often are able to take sour milk, and the milk sugar could be used in the diet in other ways as is customary with cane sugar, although sweetening qualities, who iabetes, ' The Termination of a Nerve in a Touch Corpuscle. Micrometer, and Probe Used for Testing It, by Means of Which Differences of 1-100,000 pressure of 33 grams per square millimeter, and on the back of a finger only five grams. Nearly all pressure sensation localizes itself near a hair root, and in particular, on the side opposite to the direction toward which the hair slants. "The sense of touch is greatly augmented by a profusion of hair on the skin," says Mr. Kraus. "When a slight touch is applied to the hair prop- er, it acts on the long lever arm of the hair and multiplies the force of pressure so applied five or more times, because the hair is pivoted at the surface of the skin and the arm of the lever projects through the skin, into a hair follicle profusely surrounded by nerve endings. "It has been found that before the skin was shaved, .2 milligram pressure was effective, whereas after being shaved it required a 86 milligram pressure to produce the same feeling of touch. "A different sense is that of discrimination or what is otherwise known as the spatial quality of touch. If any part of the skin of the body is stimulated by applying a cork point to the skin, you can instantly tell the exaet location of the excited spot. If now, instead of ane point, two cork points are substituted in a pair of dividers, there must be a certain dis before you are able definitely to determ whether or not there are two points or only one point in contact with the skin. "By means of the temperature senses the skin can appreciate that a body coming in contact with it is either cold or warm. If the body is of the same temperature as the skin, no sensation is generally excited. Neither are the senses of warmth and cold produced by the same.meana" same regions, cold spots can be definitely out- lined. a inv on of these warm and cold spots," says Mr. Kraus, "shows that the ap- paratus for the appreciation of cold is much more distributed over the body than that of warmth. The cold areas are best marked on the chest, the nose, the abdomen, etc. and both cold and heat are less sensitive on the face, hands and mucous membranes. We can, therefore, drink - hot drinks, which, if applied to the hand and other more sensitive parts of the body, would . prove very painful. "When the skin is very cold or very hot, it is much more difficult to recognize a of temperature." What Is Meant by Timber PECIFICATIONS often call for "virgin growth" or "second growth" timber, yet the termasare without fixed material when delivered cannot be tified as belonging to one class or the "Virgin growth," aso called "first growth" or "old growth," means timber which grew up in a standing forest under conditions of active com- petition for sunlight and moisture. "Second growth," which applied to a forest stand, ally means timber whose main growing period rred under conditions of lessened com- petition, after all or a portion of the original stand had been removed by cutting, fire, wind, or other means. In connection with individual trees, the term is used to mean an i of "VIRGIN GROWTH" As a second growth forest attains maturity, the rate of growth slows up, and the annual rings may be no wider than in n-growth timber of the same size. On the hand, when a slow- growing suppressed forest tree is freed by re- moving the neighboring trees, it may grow rapid- ly for a long period. Crherefore it is possible to have some wood with the characteristics of virgin growth and some with those of second growth in the same tree. Furthermore, individnal trees in a virgin growth forest may have the character- istics of second growth throughout and vies versa. A Friendly Poison Gas E laity would hyve some difficulty in see ing any connection between a poison gas and a clear water supply, but the wand of alectrochemist reveals The New "Language of the Air" ECAUSE of the frequency with which the B "language of the air" is not only misused, but also misunderstood, the National Ad. visory Committee for Aeronautics has just devised and compiled a standardized set of terms which have been prescribed for use in Uncle Sam's army and naval air service. Among the new and often misunderstood terms are the following: Aeronaut--The pilot of an aerostat (airship landing field equipped with hangars and shops. : Aviator--The operator or pilot of heavier than-air craft, such as airplanes and Seaplanes. Bank--To incline a plane laterally in turning to prevent skidding. Ceiling--Maximum height to which an air. plane or airship ean climb. Fuselage--Body of an airplane, including passenger seats, / Glider--~An girplane without a power plant, Helicopter--An aircraft deriving its support net from wings but the vertical thrust of pro- pellers. Nacelle--Enelosure for passengers or engines, but unlike the fuselage, it has no tail unit, Ornithopter--An aircraft deriving its support and power from flapping wings. Pancake--To land by an airplane by levelling off higher from the ground than normal, causing it to stall and descend nearly vertically. Slide Slipping--Sliding on a bank, toward the ground. Skide--Runners used with landing gear, also on lower wing tips, as a protection. Skidding--S8liding sidewise away from the ground on a bank; opposite to slipping. Soar--To fly on a level without power, Spin--An aerial manoeuvre in which the air. plane descends nearly vertically while turning rapidly in the form of a helix or a "workscrew." Taxi--To run an airplane over the ground or a4 seaplane over the water under its own power without taking the air. Zoom--To climb rapidly at a very steep angle, According to the recent published report of the national advisory committee "aireraft" econsti- tutes any form of craft designed to navigate the air and is divided into "aerostats" and "air- planes." Aerostats comprise lighter-than-air eraft, embodying a container filled with a gas lighter than air, such as hydrogen and sustained by its buoyancy. They include "airships" and "balloons." Aerial experts will tel] you that it is customary for the public to call anything that traverses the air an "airship," whereas the word "aircraft" should be employed. They say that ali balloons, rigid and non-rigid airships, or lighter-than-air craft, are constantly being termed "blimps," a word now obsolete, but originally used to designate a non-rigid airship, driven by an engine installed in an airplane fuselage slung beneath the bag. ! he word "airplane" is now used to designate craft heavier than air, obtaining their support from the action of the air on the wings, and driven through the air by screw propellers. ctors" are airplanes having their propellers in front, "pushers" having them in the rear. Usually airplanes are equipped for land werk with wheeled landing gear, but, when fitted for ting on water, with a boar or pontoons, the term "seaplane" is used. "Airships," as the craft formerly known as lighter-than-air are now called, are divided into three types; rigid, whose form is maintained by a metallic frame within -the gas bag or envelope; non-rigid, whose envelope' is kept taught by the pressure of the contained gas, and semirigid, maintained by a rigid or jointed keel and also by gas pressure. These three types are all propelled by gas engines located in a hull or car, or in in- dividual engine houses suspended below the sup- porting envelope, and controlled by means of rud- ders and fins, , "Balloons," the second division of the aerostat class, have no power plants nor means of con- trolling their horizontal flight. They include free, or flight balloons of the old-style spherical type; captive ballons used in forming an aerial barrage against airplane attacks; kite, an elongated cap- tive balloon such as the Caquot observation bal- loon, which has tail fins to keep it headed into the wind; nurse, a small heavily fabricated balloon used for storing gas and filling service balloons; and pilot and sounding balloons employed in se- curing meteorological data. The heavier-than-air types of aircraft now of- ficially termed airplanes, are divided into several classes according to the number of planes or wings, which are usually superimposed, namely: monoplanes, biplanes, triplanes and maltiplanes. There is also the Langley type of airplane, which is still ealled the tandem from the arrangement of its double set of wings on approximately the same level, : The word "hydroplane" has often been mis- used in referring to a seaplane; "hydroplane" designates a sea sled, which planes on the sur- face of the water but does not take the air. An airplane has been called an "aero," which, it is explained, is as wrong as calling a boat a "water." The words "aeroplane," "hydro-aero- plane" and "dirigible" have been done away with and "airplane," "sedplane" and "airship" have taken their places. "Seaplanes," airplanes designed to rise from or light on the water, are classified in two groups; boat geaplanes, having a central hull not unlike a boat, and float seaplanes, whose landing gear consists of one or more floats or pontoons. Rare Sugar as Diet for Disease Germs ELICATE tests are required for determin- ing the purity of rare sugars, which often are sold for several hundred dollars a pound. Rare sugars are principally used in the cultivation of disease germs for study and if these are not absolutely pure, they fail of their purpose, They are made of such unusual substances as the roots of the dahlia, from the ivory nut and from manna. y An example of the extreme accuracy of the tests required is given in the Journal of Indus- trial and Engineering Chemistry, Drs. Cagl Pfanstishl and Robert Highland Park, II. The chemists warn their fal- low-workers for instance against using in the processes any distilled water drawn from a cop- per faucet as the contact of the metal has been known to prevent the growth of certain organ- isms. They also urge that the moisture present in these sugars be kept down to a small fraction of 1 per cent. The sugars must also be kept white as organic coloring matter interferes with the brilliancy of their solutions and the detection of delicate color reactions. Making SOW'S EAR Into SILK PURSE HAT ages-old challenge that "you cannot make a silk purse out of a sow's ear," been met by 20th century. science. dence of this fact was shown at the recent Chem- xposition in New York city, at which Ar- thur D. Little, a chemist of Cambridge, Mass., exhibited such a purse. The announcement of the successful result of Sxperiments. contains 'the explanation that the is not very strotig and that there is no pres- strand. This becomes a firm filament of silk when To Make a Silk Purse Out of a Sow's Ear, Science First Analyzed the Silk. worm's Method of Making Silk, and Then Copied Its Caterpillar Chemistry in the Laboratory. ent industria! value in the process involved. It is more or less the product of chemistry at play, but a contribution alse to philosophy in proving the fallacy of erb. it coagulates on reaching the air, Analysis of this viscous liquid showed it to be like glue and with somewhat similar chemical properties. The sow's ear being chiefly gristle and skin also has the natural elements of glue. This was obtained from the ears and it was put through several processes of preparation, filtered under pressure and placed in spinning apparatus of a special design. The solution of lone and chemicals came ou: as 16 very fine color! streams, joined into one compositd fibre, treated to give it strength and color, and processed yet again to obtain the de. sired soft, silky feel. The weaving followed on a 'small hand loom, the fabric was formed and thus a silk purse was made from 5 sow's ear.