266 



Popular Science Montldy 



on the bearings and the deli\ery of 

 power in the wrong direction. A trip to 

 the repair shop ine\itably ensues, with 

 a big bill. 



An oil which has not been selected 

 with a due regard for the requirements 

 of the cylinders is bound to affect the 

 bearings. Unnecessary wear of the 

 main or connecting rod bearings is 

 caused by poor quality of the oil, or by 

 an oil too light in body, or by an oil too 

 heavy in body to reach the friction 

 surfaces, or by an oil unsuited to the 

 method employed for supplying it to the 

 bearings. When each revolution of the 

 crankshaft is accompanied by a dull 

 thump, you may be sure that this wear 

 is manifesting itself. 



Selecting the Right Kind of Oil 



The lubricating system of the auto- 

 mobile ought to be but is not standard- 

 ized. No less than ten different mechan- 

 ical methods of lubricating automobiles 

 are in use on the various cars made in 

 the United States. Some day the 

 Society of Automobile Engineers will 

 specify one lubricating system for all 

 makes of cars, and when that time 

 comes it will be easier than it is now to 

 select the right kind of oil. As it is the 

 lubricating requirements of each make 

 of car must be studied — a study which 

 involves the construction of the engine; 

 horizontal, vertical, or V type of cylinder 

 arrangement; two or four stroke cycle; 

 bore and stroke; valve construction 

 and arrangement; oiling system; num- 

 ber and fit of piston rings; piston 

 clearance; condition of the bearings; 

 cooling system (air and water); engine 

 speed; and climatic conditions. It is 

 evident that the average automobile 

 owner cannot be expected to have either 

 the engineering experience or the tech- 

 nical knowledge required to consider all 

 these factors. Fortunatch- the leading 

 oil refiners have made elaborate and 

 special studies of the many motor cars 

 on the market and ha\e prepared 

 lubricating charts, which can be obtained 

 for the asking and which show exactly 

 what oil should be selected for any 

 given make of car. In a few years from 

 now lubricating systems may be stan- 

 dardized with the result that a single 

 oil will answer fnr all motors. 



A -well-known motor car manufacturer 

 has given it as his opinion that fully 

 seventy-five per cent of automobile 

 repairs and fifty per cent of depreciation 

 in automobiles may be attributed to 

 poor lubrication. A car costing $850 is 

 operated at an annual cost of $416. Of 

 this sum depreciation, repairs, and fuel 

 are represented by $286. The amount 

 of lubricating oil required in a year does 

 not cost more than $10. It is the wildest 

 kind of folly, therefore, to save money 

 on the small amount of lubricating oil 

 required to keep down the expense for re- 

 pairs and depreciation. Cheap oils mean 

 repairs, and repairs mean hea\"y bills. 



Spontaneous Explosions Due to 

 Microscopic Plants 



EVERY little while an explosion oc- 

 curs in a subway, sewer or trench 

 or in an electric-wire tunnel or some 

 other subterranean conduit or passage- 

 way under such circumstances that it is 

 exceedingly difficult to determine the 

 cause of the accident satisfactoriK-. 

 Such explosions have often been attrili- 

 uted to sewer gas, which contains a 

 considerable proportion of methane and 

 hydrogen. These gases are exceed ingU- 

 combustible and quite capable of explod- 

 ing with extreme violence when mixed 

 with air in the right proportion and fired 

 with a spark or a flame. This much is 

 quite generally admitted; but in many 

 cases the difficulty is to account for the 

 ignition of the mixture, when it appears 

 to be impossible to ascribe it to the 

 action of any recognizable external agent, 

 such as electricity- or flame. 



It is well known that, during the de- 

 coinposition of the organic matter in 

 sewage, microscopic plants of a certain 

 kind grow in the mass and act upon it in 

 such a wa\' as to cause about two- 

 thirds of it to liquef\', while the remain- 

 ing third remains in the solid stale. 

 When the conditions are faxorable, 

 phosphine gas is occasionally generated 

 in the course of the bacterial action; and 

 this gas, when impure, has the peculiar 

 and unusual property of taking fire 

 spontaneoush- upon coming in contact 

 with the air. Such a fire spreads with 

 great r.qiidilN'. 



