| 1912 | 1916 | 1920 | |
| Alabama | 3,385 | 21,636 | 74,637 |
| Arizona | 1,624 | 12,124 | 34,559 |
| Arkansas | 2,250 | 15,000 | 59,082 |
| California | 88,699 | 232,440 | 568,892 |
| Colorado | 8,950* | 43,296 | 128,951 |
| Connecticut | 24,101 | 61,855 | 119,134 |
| Delaware | 1,732 | 7,102 | 18,300 |
| District of Columbia | 1,732* | 13,118 | 9,712 |
| Florida | 1,749 | 20,718 | 57,000* |
| Georgia | 19,120 | 47,579 | 144,422 |
| Idaho | 2,500* | 12,999 | 50,750 |
| Illinois | 68,073 | 248,429 | 568,759 |
| Indiana | 54,334 | 139,317 | 332,707 |
| Iowa | 47,188 | 198,602 | 437,300 |
| Kansas | 22,000 | 112,122 | 265,396 |
| Kentucky | 5,147 | 31,700 | 112,685 |
| Louisiana | 7,000* | 17,000 | 66,000 |
| Maine | 7,743 | 30,972 | 62,907 |
| Maryland | 10,487 | 44,245 | 105,000* |
| Massachusetts | 50,132 | 136,809 | 304,631 |
| Michigan | 39,579 | 160,052 | 412,717 |
| Minnesota | 29,000 | 46,000 | 64,312 |
| Mississippi | 2,895 | 25,000 | 64,000 |
| Missouri | 24,379 | 103,587 | 295,817 |
| Montana | 2,000* | 24,440 | 60,646 |
| Nebraska | 33,861 | 100,534 | 223,000 |
| Nevada | 900* | 4,919 | 10,464 |
| New Hampshire | 5,764 | 17,508 | 34,680 |
| New Jersey | 43,056 | 104,341 | 226,459 |
| New Mexico | 911 | 8,228 | 22,109 |
| New York | 107,262 | 317,866 | 651,796 |
| North Carolina | 6,178 | 33,904 | 140,860 |
| North Dakota | 8,997 | 40,446 | 90,840 |
| Ohio | 63,066 | 252,431 | 616,800 |
| Oklahoma | 6,524 | 52,718 | 204,300 |
| Oregon | 10,165 | 33,917 | 103,790 |
| Pennsylvania | 59,357 | 230,578 | 570,164 |
| Rhode Island | 8,565 | 21,406 | 50,375 |
| South Carolina | 10,000* | 19,000* | 92,818 |
| South Dakota | 14,481 | 44,271 | 122,000 |
| Tennessee | 9,973 | 30,000 | 101,852 |
| Texas | 35,187 | 197,687 | 427,634 |
| Utah | 2,576 | 13,507 | 42,604 |
| Vermont | 4,283 | 15,671 | 31,625 |
| Virginia | 5,760 | 35,426 | 134,000 |
| Washington | 13,990 | 60,734 | 175,000* |
| West Virginia | 5,349 | 20,571 | 78,862 |
| Wisconsin | 24,578 | 115,637 | 293,298 |
| Wyoming | 1,300 | 7,125 | 23,926 |
| Totals | 1,007,882 | 3,584,567 | 8,887,572 |
| *Estimated | |||
and after the outbreak of the World War. During the former period development proceeded normally, from both a technical and a commercial standpoint. Great Britain had the greatest number of cars in use, but France was the greatest producer, about one half of the French production being exported. In continental Europe the introduction of motor-cars was hampered by heavy taxation on the cars themselves and on the fuel. The use of motor-trucks, on the other hand, was encouraged by the so-called subsidy system, by which purchasers of trucks suitable for military purposes were offered by their Governments a bonus on the purchase price and also on the upkeep cost, in considera- tion of their keeping the trucks always in fit condition and agree- ing to turn them over to the Government in case of war. Great Britain, France and Germany had such subsidy systems before the war; Japan adopted the same policy later. As soon as war was declared the motor-car factories were set to work for the war departments, either making trucks or other vehicles for the transport corps or else manufacturing aero-engines or munitions. Soon all the petrol available was needed in war service and the use of motor vehicles by private parties practically ceased. In England some use was made during the war period of town gas for motor fuel; this was carried in a collapsible bag of rubberized fabric, on the roof of single-deck omnibuses for instance. With this fuel it was possible to obtain about 85% as much power from an engine as with petrol, and a satisfactory mileage on one filling was secured. Under normal conditions the gas would have been carried in steel bottles under high pressure, but owing to military requirements no steel could be spared for this purpose. The Cen- tral Powers suffered much more from fuel shortage than did th Allies, and extensive researches on substitute motor fuels were carried out in Germany. After their petrol supply ran low the Germans used benzol, petroleum mixtures, benzol-alcohol mix- tures, alcohol, wood alcohol, tar oil, gas oil and shale oil, as well as compounded fuels known under the names of electrol, bene- dixine and melanol. Shale oil was derived from a raw material said to be intermediate between bituminous clay and lignite. Benzol was recognized as a valuable motor fuel, and its use con- tinued, even after petrol was again available.
Registration in Great Britain. The British Ministry of Trans- port during the summer of 1921 issued a statement of the num- ber of motor vehicles of different kinds for which licences had been issued under the new motor vehicle tax law during period Jan. i-May 31 1921. These included 212,000 privat passenger cars, 370,000 motor-cycles, 95,300 public passenge vehicles and 16,000 lorries. According to the same authorit there were licensed in Great Britain on March 31 1920, 185,70 private passenger cars, 278,600 motor-cycles and 71,400 public passenger vehicles, there being no record of the number of lorrie for that dale.
Registration in the United States. The figures given in Tabl I are based on information furnished to Automotive Industrie. by the registration officials of the different states. Allowance were made for re-registration of cars sold by their owners dur- ing the registration year and for registration of cars by non- residents, and the table is believed to give as accurately possible the number of cars in service in each state during the years mentioned by residents of the respective states.
Registration in Canada. Table II. shows that from 1915 to 1919 the number of cars registered increased over 279%.
| Province | 1910 | 1915 | 1919 |
| Ontario | 4,200 | 42,346 | 144,804 |
| Saskatchewan | 531 | 10,225 | 56,855 |
| Quebec | 786 | 10,112 | 33,547 |
| Alberta | 423 | 5,832 | 34,000 |
| Manitoba | 1,524 | 9,225 | 30,118 |
| Br. Columbia | 1,026 | 8,360 | 22,420 |
| Nova Scotia | 148 | 1,841 | 10,290 |
| New Brunswick | 299 | 1,900 | 8,306 |
| Prince Edw. I. | — | 35 | 790 |
| Yukon | — | 69 | 89 |
| Totals | 8,937 | 89,945 | 341,219 |
Technical Developments. In 1908 the "Silent Knight" engine, invented by Charles Y. Knight of Chicago, was adopted by the Daimler Motor Co. of Coventry, England, and within the next few years licences for its manufacture were taken out also by leading manufacturers of France, Belgium and Germany. This engine was notable for its almost silent operation, due to a form of sleeve valve employed, and its introduction had a strong influence on engine development in general during the next few years. In the Knight engine (fig. i) the usual poppet valves are dispensed with, and in- stead there are two concentric sleeves between the piston and the cylinder wall. These sleeves are reciprocated by means of short connecting rods from .a short-throw crankshaft which is driven at one-half the speed of the regular crankshaft; when ports in the two sleeves and in the cylinder wall are in register there is com- munication between the combustion chamber and either the inlet or exhaust manifold. In 1908 noise was one of the most serious objections to the ordinary motor-car, and designers of poppet-valve engines were spurred on by the competition of the Knight engine in their efforts to make their engines silent too. They achieved re- markable success by lightening the valves and parts reciprocating with them, by refining the cam outlines, stiffening the camshafts, adopting silent drives for the camshafts and enclosing the valve mechanism. A most desirable feature in a motor-car is flexibility, that is, the ability to pass from a low to a high speed by merely opening the throttle valve. This is secured by using an engine of great piston displacement (a powerful engine) in proportion to the combined weight of the car and load. The much better performance of modern cars, as compared with earlier ones, from the control or " handling " viewpoint, is largely due to the use of much greater piston displacement relatively. American cars have been specially noted for their flexibility, due to the use of very large engines not with- standing high fuel consumption per mile travelled. As motor fuel was much more expensive in Europe, European designers could not ignore the factor of fuel economy as American engineers could.
In engine design the constant endeavour was to get greater output from an engine of given piston displacement. Horse-power output
