Popular Science Monthly 



773 



be taken to keep the red lead from working 

 up into the paint above it, if the latter is a 

 light color; hence the coat next to the red 

 lead should be rather stout. Or you may 

 make the second coat of paint with plaster 

 of Paris and boiled linseed oil to the con- 

 sistency of buttermilk, added to *a batch 

 of white lead paint made of the same 

 consistency as the plaster paint; mix well 

 together, and thin out to a brushing con- 

 sistency with turpentine. This coat should 

 be made as heavy as you can well brush 

 it out. The next or finishing coat should 

 be ordinary oil paint, drying with a gloss, 

 the same as used on outside woodwork. 

 The reason for applying the plaster paint 

 is that it prevents the subsequent coats of 

 paint from wrinkling or running where 

 much paint is to be applied. It must be 

 made to dry quickly, by means of dryers, 

 so that you will not make the mistake of 

 applying the succeeding coat prematurely, 

 in which event there would be cracking 

 of the paint. Observe particularly that no 

 plaster is to be added to the last coat. 



It should be said, in conclusion, that no 

 oil paint is really waterproof, because 

 linseed oil is not proof against moisture. 

 This can readily be demonstrated by sub- 

 jecting a dry coating of linseed oil paint to 

 the action of water. Note how the coat 

 whitens and swells, showing that the oil 

 has taken up water. — A. Ashmun Kelly. 



Two- Speed and Reverse Countershaft 

 for a Small Lathe 



THE countershaft illustrated was de- 

 vised and built for a small screw 

 cutting lathe which was used for a great 

 variety of work, from turning hard steel 

 to high-speed wood turning, thus requiring 



Countershaft cone 



Pulleys of different diameters with three ship- 

 per levers to provide many different speeds 



a wide range of speed. Two forward speeds 

 and one reverse were provided, and as the 

 lathe was furnished with back gears, the 

 arrangement gave twelve speeds for normal 



use and six for the reverse, the speed range 

 running from 30 to 1000 r. p. m. 



The three shipper levers were arranged 

 conveniently near the head of the lathe, 

 one behind the other, the low-speed lever 



Countershaft 



Three levers to op- 

 erate the belts for 

 two- speed forward 

 and one backward 



in front, next the high speed and then the 

 reverse, which happened to be an iron 

 lever. Had it not been of iron it would 

 have been provided with a different shaped 

 handle so that the operator would not be 

 likely to throw it in by mistake. Tight 

 and loose pulleys without friction clutches 

 were used, those on the countershaft being 

 of the same size, of iron, while the line 

 shaft pulleys were of different diameters, 

 and were of the straight face wooden 

 type. — H. H. Parker. 



The Damage Caused by Running 

 Tires Deflated 



RUNNING a tire deflated for even a 

 . short distance is harmful to the tire 

 and extravagant. When traveling at a very 

 high rate of speed it may of course require 

 some time to bring the car to a stop. But 

 a certain amount of damage is done every 

 second of deflation. A soft or flat tire on 

 a front wheel can always be noticed by the 

 difficulty in steering the car in a straight 

 course — the steering wheel naturally veers 

 toward the side of the flat or soft tire. 

 If there is a deflated tire on the rear 

 wheel, pounding and bumping will be 

 noticeable. A rear tire ridden flat very 

 far will result in damage to the differential. 



