In selecting a lubricator for any rubbing surfaces, care must be taken to adapt the character of the lubricating material to the nature of the rubbing surfaces and the weight which they have to sustain. A fine, thin oil is useless for heavy bearings, and a hard, stiff soap, which would be excellent for such bearings, would be a poor article for a very light piece of machinery. In the case of heavy bearings, such as railway exles, when they once begin to heat and cut, it will be found impossible to prevent heating by the mere application of oil. The surfaces of the metal must be worked over either by grinding or the turning tool. Thus, when journals heat at sea, the usual custom is to use sulphur, black-lead, or water; but the relief they afford is only temporary. The following is a method that gives permanent relief: When you find the journals getting hot, slack back the nuts on the cap from one-quarter to one-third of a turn, and supply the journal freely with dust procured by rubbing two Bath bricks together, mixed in oil to a consistency a little thinner than cream. After a short time begin cautiously to set up on the nuts; and before finally bringing the nuts to their original position, give a copious supply of oil alone to wash out the journal; then bring the nuts into position, and you will have no further trouble. This plan has also been tried on railway journals, and it has been found that a handful of clay or gravel has effected that which gallons of oil and water could not do.

In addition to the usual oils and grease the following lubricators deserve attention:

1. Plumbago

This material is gradually coming into use, and when properly selected and applied it never fails to give satisfactory results. It may be used on the heaviest planers and ocean steamers, or on the lightest watchwork. When applied to delicate machinery the surfaces should be very lightly coated with the plumbago by means of a brush. In this Avay all danger of grit is avoided. Plumbago seems to be specially adapted to diminish the friction between porous surfaces, such as wood and cast iron. For the cast iron beds of heavy planers it is a specific.

2. Anti-Attrition

Mix 4 lbs. tallow or soap with 1 lb. finely ground plumbago. The best lubricator for wood working on wood. Excellent for wooden screws where great power is required.

3. Fine Lubricating Oil

Put fine olive oil in a bottle with scrapings of lead and expose it to the sun for a few weeks. Pour oil' the clear oil for use. Another method is to freeze fine olive oil, strain out the liquid portion and preserve for use.

Booth's Axle Grease

Dissolve 1/2 lb. washing soda in 1 gallon water and add 3 lbs. tallow and 6 lbs. palm oil. Heat to 210° Fahr., and keep constantly stirring until cooled to 60° or 70°.