The invention is not only a plaything. It can be made useful in the distribution of pamphlets, or newspapers, which can be introduced into the box folded uniformly. They can also be used in omnibuses or tram-cars, and tickets may be given by the machine on payment of the proper sum of money.
We will close this chapter with an illustration of a spiral bottle, which can be done in the manner now to be described, so that the bottle will actually become a glass spring.
Take a mixture of 180 grammes of lampblack, 60 grammes of gum arabic, 23 grammes of adraganth, and 23 grammes of benzoin. Make these ingredients into a paste by the addition of water, and fashion a pencil of the charcoal thus obtained. This pencil, when heated, will cut the glass wherever it is applied.
The process is commenced by scraping the bottle with a file and following the instrument with the red-hot pencil. Wherever the hot pencil is applied, the glass will be cut as shown in the illustration herewith. It will be necessary to blow upon the heated pencil to maintain the incandescence as long as possible. The bottle as cut and representations of the instruments are given in the cut (fig. 873).
Fig. 873. Spiral bottle.
CHAPTER LVIII.
SCIENTIFIC OBJECTS FOR THE HOUSEHOLD.
