Waste of Electricity in Lighting.--In large residences where a good many servants are employed or in any place where the power consumed is not directly under the supervision of the person who must pay the bills, a great deal of waste usually occurs. If the meter be read before retiring, the reading in the morning will show how much energy was consumed during the night, which will show in turn how many lamps were burning all night. A great deal of light can be saved by placing the lamps so that they will throw the light where it is needed and by placing small lamps such as 8 candle power and 4 candle power in places where not much light is needed, such as bathrooms, halls, cellars, etc. When the lamps get old and dim they should be replaced with new ones, as it costs about the same to burn an old lamp as a new one. An old 16 candle power lamp which is very dim will give only about 8 candle power and use about as much current as is required for a new 16 candle power. If the dim light be light enough, it should be replaced by an 8 candle power lamp, which will not consume as much power as the old 16 candle power. CHAPTER XXIX OPERATION OF DYNAMOS Before Starting a Dynamo or Motor.--When the machine has been securely fixed, it should be carefully examined to see that all parts are in good order. The examination should be made as follows: 1. The field magnet circuit should first be inspected to see that none of the wires or connections have broken or have become loose, and that the coils are correctly connected; 2. The caps of the bearings should be taken off, and these and the journals carefully cleaned of all grit and dirt. They should then be oiled, and the caps replaced and screwed up by hand only; 3. The gaps between the outer surface of the armature and the polar faces should be examined in order to ascertain whether any foreign body, such as a small screw or nail has lodged therein. If such be the case, it should be carefully removed with a bit of wire; 4. The guard plates protecting the armature windings should be removed, and the windings carefully inspected by slowly rotating the armature, to see that they are not damaged, and that the insulation is perfect. The armature should then be finally rotated by hand to see that it revolves freely, and that the bearings are securely fixed; 5. The commutator should be examined to see that it is not damaged in any way through one or more of the segments being knocked in, or the lugs being forced into contact with one another; 6. The brush holders and brushes should be inspected to see that the former work freely on the spindle, and that the hold off catches work properly, are clean and make good contact with the brush holders or flexible leads; 7. Having ascertained that the machine is not injured in any way, and that the armature revolves freely, the brushes should be adjusted.