Collisions between trains and vehicles standing foul of the line .
Collisions between passenger trains and goods or mineral trains or light-engines .
The first actual collisions, the Cecora campaign of 1620 and the Khotin War of 1621 (for John Albert's Moldavian raid does not count), were due to the depredations of the Cossacks upon the dominions of the sultan by land and sea, and in all subsequent treaties between the two powers the most essential clause was always that which bound the Republic to keep its freebooters in order.
The question could not be settled by experiments made at the same temperature, and if the temperature is altered the question is complicated by the distinction which would probably have to be drawn between the number of collisions and their intensity.
The beginnings of Austrian sovereignty were marked by many collisions between the representatives of the new rulers and the States General, and provincial " states."