(5) Many troubles result from the use of unsuitable methods of oil application, and from failure to give the required attention in order to maintain a sufficient uniform supply of the oil. The effectiveness of hand oiling depends on the attendant. The oil is applied periodically in a quantity greater than is necessary for the momentary need, much of the oil escaping from the bearing without rendering service. Commonly the period between hand oilings is so great that lubrication becomes inadequate, and with neglect a condition of actual non-lubrication occurs. Drop feed oilers, although far superior to hand oiling, do not give a uniform feed, and may at any time become clogged and cease to provide lubrication. Drop feed oilers may be replaced by bottle oilers on small bearings and by wick-feed oilers on large bearings, with improved reliability and economy of lubrication. Whatever the method of oil application, neglect with regard to supply or cleanliness is certain to lead to trouble sooner or later.