Page:Cyclopedia of Puzzles by Samuel Loyd.pdf/32



I STARTED two watches at the same time and found that one went two minutes an hour too slow, and the other one minute an hour too fast, so that when I looked at them again the faster one was exactly one hour ahead. Can you ﬁgure out from the dial at what time. before noon the watches must have started?

Here is another our which will puzzle you: How soon will the hour, minute and second hands again appear the same distances apart, as shown above?

Such problem- are built upon the immutable laws of the tbvi run of time and are therefore purely mathematical and mechanical, 1'hcre arc 60 seconds to a minute, and OG minutes Lu aii hour, thfrefore there an■3 .600 seconds to an honr, and that is all there is to it. ahliongh there are many clever and very puzzling problems ornate cted with watches

and clocks. When I W&S a very little lad I learned that a pendulum ■TT1 inches long would beat a true second, i was very fund of ri lining so I used to carry a bullet attached to a siring of that length, which would swing from a pin >tuck in the fence so Mint I could time the buys racing. I became infatuated with dn; sport and have run many races in all quarters of tile globe and in innumerable cases can thank the early tm i in., ■ t my Srgs fur saving my skin, and at time- -, Ufe.

l may say, while upon the subject, Thai to run 100 yard - in o seconds is the limit of speed, J have seen it run in that dm*, fecit there is no professional Hvfnr- who can dir it. Amwriters ami smart boys, with the aid of a bullet and string will fmd their

spe. d to be somewhere between ten and twenty seconds, and may derive great pleasure, as by constant practice they reduce their record down the friction of a second at a time.

For practical use the bullet and string may he '*£5 inches long then

h will count half a second in its Ewing from right to k-fl.OT one whole accon- l m die swing,jf forward and back; Ibis enables one to count the half and quarter seconds.

The remarkable fact of a 39.1 pendulum beating a true second in its swing, whether it travels tv. . feet each time, or one root, or on! one nidi, h the principle which rcguJatcs all clock*, ami even watches'.' The hair spring connected with the escapemem of a watch utilizes the elasticity of die spring in place of gravity.

I he only obstacle to perfect lime indicating is that the pendulums lengthen^ when the temperature is warm, I his fault i- overcome by ingenious compensating devices for correcting the length of the pendulum by the use of two metals of different expan- i vc power.

t once constructed a


 * 1) c1oek out of wood which kept excellent time, Here is how T utilized the "gridiron" principle ti« regulate ^ the centre of oscillation. The rods A A are made of


 * wnod wkirh expands Tut little from heat, 13 i: made of _ metal which expands twice ai much, so where A 1 e n. gi 3 1 en a Lh e pendu I uma tittle. E exp i mils twice a; much and shortens it again.

Pendulums must be of different lengths In different parts ot the earth on account the variable attraction of gravitation. The rule for getting the length of a pendulum is known by mathematicians as "pi time.* lEu- square root of the length of the pendulum (in Indies) divided by gravity."

A falling body goes 16 feet the first second; 5 times lu die next second. 5 timej Id the third second, ami's j ~- on iricri asj -ag according to die odd numeral^ 7, 9, 11 time:, is fast, ami by ibis rule we make our clocks and watches! Here is a pretty problem to conclude with for the expert mathematician* to ponder over: If a pendulum vibrates as

often >n a minute as it ha;: indies in its length, haw long is iff

The watch was invented at Mu rube rg aL the end of the 15th century* but was of no practical value until Dr Hooke invented the hair- spring in 1653. The time-keeping; qualities of a watch depends altogether on the perfection of the qfcapcjncnt which performs the part of a pendulum* I have a $1,000 Jorgenson repeater which ring- the hours, quarters and minute f, limes tin- horse and docs all sort- of stunts. Thu manufacturer of an American watch presented mi- with a time-piece and asked me to keep a carefiil tally un the two watches for three luumEis; \ did St), and el ieer fully give credit to the American product which beat Lite other out by one minute and ten secand*. To show my sporting blood.

1 offer to put up [hat watch against the best di Tonometer in the world, the One which keeps the best time fur three months to take both watches. A? a boy I remember reading about the days when they depended upon hour glasses and sun-dials, so J constructed a sun-dial which kept perfect time Here is a pattern for Ihu uI'.'vt lads to follow after, wlnuri

CttllS I J particular directions j

Just paint the dial, as shown, upon a piece of hoard; let the pointer run up about at an angle of 45 degrees; sr\ Lite ill iJ very level with 12 pointin i \ c x:ic r.ly iinrl.li and (Ik ahadu w Indicates •he hour. In l he sketch it is pointing lo half past one.