It is now ready for the motive power, which is obtained by the falling of sand, as in the hour-glass. The sand must be first well washed, dried, and sifted, to remove all stones, then poured through the case top to within two inches of the cross-bar (C, Fig. 18), the weight resting on the surface. As the sand runs through the funnel-point the weight will descend with it at the rate of about 1 in. per hour. The flow of sand will be perfectly equable from the time the case is filled until it is nearly empty, which is explained by the fact that the sand lies in a succession of conical heaps, only the _first_ of which presses on the bottom, the others throwing their weight on the sides of the case. A gallon of sand will be more than sufficient to fill the cases, and as it falls it should be caught in a vase placed beneath for that purpose. In winding up the clock the inside weight must be raised to the cross-bar by pulling down the bullet end of the cord, and the sand poured through a paper funnel into the top of the case, care being taken to set the hand to the right hour. A clock of the dimensions here given will work for about twelve hours, but by lengthening the sand-box the working hours will be increased in proportion. It will save time and trouble to have a double supply of sand and two vases, and use them alternately. Of course one does not pretend that such a simple clock as this will keep accurate time.
CHAPTER VIII.--HOW WE MADE A CHRISTMAS SHIP.
BY C. STANSFELD-HICKS, Author of _Yacht and Canoe Building_, &c., &c.
‘What shall we do to amuse the boys?’ was the question asked at a friend’s house. ‘They are tired of Christmas trees, and it is so difficult to think of anything new.’
‘Well,’ I suggested, ‘why not have a Christmas ship?’
A Christmas ship! We never heard of such a thing! What is it?’
[Illustration: Fig. 1.--THE GOOD SHIP SANTA CLAUS.]
And this was the commencement of the planning and building of the vessel in question. To commence was a comparatively easy matter, but before she was finished and ready for her cargo the shipbuilders got rather weary. But you see they had to do everything for the first time, and with little or no previous experience. By attention to the details given in this chapter, those who go in for this Christmas ship will get on faster than we did, profiting by our experience, and not having to retrace their steps and do things over again, which was often the case with us in our first attempt.