APPENDIX A. 



Mathematical Formulas. 



TT = 3.14159. 



Circumference of circle K D. 



Area of a circle = TT R 2 . 



Surface of a sphere = 4 TT R 2 = n D 2 . 



Volume of a sphere f TT R 3 = | TT D 3 . 



APPENDIX B. 



Soldering. The teacher or pupil will often find it very con- 

 venient to be able to solder together two pieces of metal. The pro- 

 cess here described is very simple and will answer in most cases. 

 A bit of soft solder, the size of a hazlenut, may be had gratis of any 

 good natured tinsmith or plumber. Cut this into bits the size of a 

 grain of wheat and keep on hand. Dissolve a teaspoonful of zinc 

 chloride (muriate of zinc) in water and bottle it. It may be labelled 

 "soldering fluid." If you have not a spirit-lamp obtain one, or 

 make one. A small bottle (such as those in which school-inks are 

 commonly sold) will answer your purpose. Get a loosely fitting cork 

 and through it pass a metal tube about an inch long and the size of 

 an ordinary lead pencil. Through this tube, pass , bit of candle 

 wicking. Fill the bottle with alcohol, insert the cork, with tube 

 and wick, and in a few minutes the lamp is ready. Having now 

 the necessary materials you are ready for work. For example, sup- 

 pose that you are to solder a bit of wire to a piece of tinned ware. 

 If the wire be rusty, scrape or file it clean at the place of joining. 

 By pincers or in any convenient way hold the wire and tin together. 

 Put a few drops of " soldering fluid" on the joint, hold the tin in 

 the flame so that the wire shall be on the upper side, place a bit of 

 solder on the joint and hold in position until the solder melts. Re- 

 move from the flame holding the tin and wire together until the 

 solder has cooled. The work is done. If you have a "soldering- 

 iron," you can do a wider range of work, as many pieces of work 

 cannot be held in the lamp flame. 



