Apeil 20, 1917] 



SCIENCE 



391 



Speed Governors for Motor Truclcs: Theodore 



Douglas. 



There are various types of governors available of 

 ■which about 95 per cent, are of the centrifugal va- 

 riety. The constant-engine-speed governor ties up 

 from 20 per cent, to 50 per cent, of the power 

 capacity of the engine and sacrifices both gasoline 

 and engine efficiency. The constant-vehicle-speed 

 governor regulates only the vehicle speed and sac- 

 rifices the engine through allowing a prohibitive 

 speed on low gears, and no control at all in idling. 

 It is shown that the ideal governor would be a 

 combination of the constant-engine-speed and the 

 constant-vehicle-speed governors. A governor of 

 this combination type is now available in the in- 

 dustry. 



This governor may be broadly described as a 

 combination of two-speed controls operating a 

 single centrifugal unit and actuating a single 

 valve. This is accomplished through the employ- 

 ment of two sprLngless pawl clutches so designed 

 that each may overrun the other. Whether the 

 speed from the engine or from the vehicle is the 

 higher speed, that speed will engage the centrif- 

 ugal unit and close the valve. 



By the use of the combination type governor, 

 truck efficiencies have been largely increased, and a 

 perfect automatic control has been supplied. 



Factors controlling Maximum Overall Dimensions 

 of Motor Trucks: Alfred F. Masuey. 



Traffic Census Analysis: William H. Connell. 



In order to work out a suitable highway design, 

 it is necessary to make a study of the traffic con- 

 ditions, and upon the collection of adequate data 

 and its careful analysis may be based: (a) the 

 plan of a highway with respect to its lines, grades, 

 widths and location of roadways, footways and 

 lawn areas; (&) the design of a pavement surface 

 and base best suited to the traffic requirements; 

 (c) an estimate of the probable relation between 

 traffic service and maintenance costs; (d) the 

 character and time of cleaning best suited to the 

 prevailing types of traffic; and (e) the physical 

 regulation of traffic with respect to the direction of 

 flow, crossings, parking areas, safety islands and 

 zones, and safety and regulating signals. 



The several lines of investigation which are 

 necessary to a comprehensive traffic study may be 

 indicated as follows: (a) the survey, which deter- 

 mines the nature of the existing physical and other 

 conditions influencing or relating to the traffic; 

 (b) the census, which records the quantity, char- 

 acter and weight of traffic; and (c) the planning, 

 through which it is sought to develop a more con- 



sistent relation between traffic requirements and 

 traffic provision. 



In most traffic census, it has been the general 

 practise to consider "ton of traffic per foot width 

 of pavement" as a proper unit. It would seem 

 that the most logical and satisfactory unit of 

 traffic measurement would be the ' ' ton-mile ' ' or 

 its multiples per foot of maximum travelled width 

 of pavement. 



The Most Satisfactory and Economical Pavement 

 for ParTcway Drives : Samuel Whinery. 



Present Status of Preliminary Location and Map- 

 ping of National Highways proposed hy the Na- 

 tional Highways Association: Charles Heney 

 Davis. 



Possible Variations of Physical Properties of Bock 

 from One Quarry: Charles P. Berkey. 



Stone and Concrete Foundations from the Stand- 

 point of Efficiency and Economy: George C. 

 Waeren. 



The words "Efficiency and Economy" each in 

 their broadest sense mean practically the same 

 thing and the same as the word ' ' best, ' ' when con- 

 sidered in its broadest sense of ' ' all things con- 

 sidered. ' ' 



There is no one ' ' best ' ' for all conditions and 

 an engineer who would recommend any one type of 

 pavement surface or foundation as universally best, 

 would be like an architect who specified one class 

 of building material as best for all buildings, i. e., 

 a ' ' man of one idea. ' ' 



In determining the character of foundation best 

 suited for any particular case, the engineer or road- 

 builder should give most careful consideration to 

 the character of subsoil, traffic, wearing surface to 

 be laid on the foundation, and climatic conditions. 

 Block pavements of all kinds should be almost 

 universally laid on concrete foundations. Mono- 

 lithic bituminous pavement surfaces depending on 

 stability of the surface and local conditions out- 

 lined above, may be laid on either rolled broken 

 stone or concrete foundations. 



Concrete includes any dense combination of min- 

 eral aggregates in which the coarser sizes pre- 

 dominate artificially bound together with either 

 Portland, bituminous, or any other type of cement. 

 Generally speaking, broken-stone foundation is 

 adapted for cases where the rolled subgrade is of 

 a character of material which can be solidly com- 

 pressed. It has been found that sand provides a 

 good sub-base provided the sand is sprinkled dur- 

 ing the rolling of the broken stone, thus providing 

 a sub-base condition like damp sand on the beach. 



