The Birmingham age-herald., 1918-04-29
TESTING OTHER WOODS

lESlING OTHER WOODS Careful investigations and tests point l to the use of at least one other wood Tor airplane frames, and perhaps two tlr promises to be good substitute, having higher specific strength than spruce, but somewhat heavier and not the equivalent in sustaining shocks Cy- press also seems to be promising at this stage of the experiments and probably walnut or oak many be found a satisfac- tory substitute for mahogany in airplane propellers.
 To meet the shortage of chronometers 1 in navigating our new mercantile fleet l Uncle Sam is Working With the American watch industry to provide something just as good-a new substitute in the shape of the ships watch.
 This is a somewhat larger watch than one would want to carry in his pocket mounted cushions in a mahogany | chronometer box to withstand the vibra- tions, shocks and swayng aboard even a porpedo boat, which gives probably the hardest service conditions for ship | timepeces. The specifications for these ships watches were drawn up by the | bureau of standards. They are now be- | ing made in quantities and under the | rigid tests of the bureau of standards l have shown high accuracy. so that with three aboard each ship, giving check | upUll tdCH Olcl, tHty SHOu1d Dc dS ohl- | isfactory as cronometers. Incidentally, | they are much cheaper, costing less than 1 $1OO as against several hundred dollars l for a reliable chronometer and that is I a consideration even in war times when 1 Uncle Sam must provide thousands of them.
 The bureau also tests thousands of ships clocks, of which two types have l been developed one a timepiece of con- h1a and cost for locations where differences of 1 minute daily are a consderat ation, and the other a cheaper | clock for the forecastle and other places, not much more expensive than an alarm clock.
 I One gets a quiet thrill in the room where the ships clocks are tested, for l they hang in checkerboard rows, hun dreds together all busily ticking, a fairy | like rustic that makes them seem not meohanisms but personalities. war work | CTS, actual soldiers drawn up in ranks 1 for inspection, each conscious of its call | to the national service. The more cost | ly types of ships clocks strike ships | bells musically every half hour, and the visitor thinks of the many ships upon which these clocks will ultimately serve, and the dangerous watches on submarine infested ocean routes. But the men who 1 test timepieces say that they neither hear them tick nor strike-Hish, the lord Of silence has cast spell upon them such | as he placed upon the cricket who would not be silent with the other creatures ! of the night. and so Hish decreed that l n fer be had chirped 1000 times his voice should be heard no more but become l part of the silence.
 | This department also tests stop 1 watches to be used for artillery wotk 1 q form of timepiece requiring hlgh ac- ou1acy because thousands of them. will | he used to lay barrage fire and tune | other close teamwork between artll- | Ierys and infantry on the battle 1ront l I5ncle sam provides stop, watches to officers through the ordnance depart ment They split second up into 1 6fths. so that one can measure such | intervals exactly with a very little l nra ctice. They do not indicate hours 1 or minutes like an ordinary watch, but are made with a minute face only, the hand starting around a dial the size of an ordinary watch completing the | circuit in one minute by hfthS or | second, and being checked upon any | particular fifth second by pressure on 1 the stem. To test 100 of these watches | is a months work for trained man. TESTING INSTRUMENTS | In another department rigid tests l are being made of airplane instru- ments When the aviator goes aloft nowadays he has on the instrument | board before him quite a complex lit | tie collection of indicators for different | purposes He must know the timS 50 1 there is a special type of airplane l clock really large watch in its mech I anism. The vibration of an airplane 1 in service puts timepieces at decided 1 disadvantage, and thees airplane ] clock watches are mounted on board
 hich is subjected to the same vibrd- l tions they must withstand in flight. Ire testing board is operated by mo
 tor and can be filled with timepieces
 ard left to run through the night, or stopped automatically at whatever l hour is desired as the period of test
 The same test is given timepieces for
 | torpedo boats, and as test of what the bureau of standards knows as toughness--the ability to keep time
 under vibration and shock-these time pieces are rather literally shaken up
 and even dumped on the test board
 and held to standards of not more
 than three seconds a day variation.
 The airman has an altimeter which
 shows him how high he is flying-an instrument which operates by measur-
 ing the air pressure giving altitude
 1 When he gets into the clouds and loses
 sieht of the earth there must be in-
 | struments to show him the true level
 both sideways and forward, so he has
 il.clinometers of two types, lateral and
 Longitudinal, The lateral inclinometer
 is a crescent-shaped spirit level. and
 when the wings of his airplane are
 level it's bubble appears at the center
 of the crescent. The Longitudinal in
 clinometer is a spirit level with an iii-
 dicator something like q thermometers
 the bubble rising and falling with the
 | upward or downward inclination oi
 | the airplane's nose. The birdman mus;
 know how fast he is flying, and for
 this is provided with an airspeed in
 dicator. which measures his speed by
 1 the rush of air. indicating it on a dial