552 fenner: babingtonite from passaic county 



V. general inferences 



17. Relating to the coordination of existing data. Since, by 



equations (11) and (12), the laws of lubrication may involve, in 



fin . . (^ I , 



addition to the variable — , any of the quantities -^, j:, S, and 



the r's, in attempting to coordinate data obtained by different 

 observers we must consider the possible influence of all these 

 factors. 



18. Relating to future experiments. (1) In formulating the 

 laws of lubrication it has been seen that fx, n, and p can occur 



only \Yhen combined into the single variable ; hence the in- 

 fluence of all three of these quantities may be found by experi- 

 menting with any one of them. (2) It is legitimate to deter- 

 mine the dynamical and thermal properties of bearings by 

 separate experiments. For example, the laws of friction may be 

 studied under isothermal conditions; while thermal character- 

 istics, such as the constant k of equations (23) to (28), might be 

 determined with a perfectly stationary dummy bearing, in which 

 the heat is generated by a heating coil instead of by friction. 

 (3) The conception of dynamically similar bearings will make it 

 possible to evaluate the constants needed in design by the use 

 of models without waiting for the complete determination of the 

 laws of lubrication. 



MINERALOGY. — Bahingtonite from Passaic County, New Jersey. 

 Clarence" N. Fenner, Geophysical Laboratory. 



In the deposits of zeolitic minerals occurring in the Watchung 

 trap ridges of northern New Jersey certain cavities which are 

 found in abundance evidently testify to the former presence of 

 some mineral which has been removed in solution. These 

 cavities or casts are familiar to many mineralogists who have 

 visited the localities referred to and the nature of the mineral 

 which formerly filled them has been a matter of considerable 

 speculation, but no very satisfactory conclusion has been reached. 



The casts are seen most frequently among masses of quartz, 



