articulation between the pairs to effect steering. At least two prototype vehicles were constructed: one was steam powered the other used a gasoline engine. The prototypes worked well on hard packed snow but failed in soft powder because the flanges had nothing to grip into. The machine was designed to haul logs, but its length and rigid construction meant that it had difficulty with the uneven winter roads for which it was intended. Peavey's invention could not compete with the Lombard Steam Log Hauler built by Alvin Lombard and it was not produced commercially. (The Lombard vehicle was an early example of a half-track vehicle, it resembled a railway locomotive with a sled or wheels in front for steering and caterpillar tracks for traction.) Armstead Snow Motor In the 1920s the Armstead Snow Motor was developed. This was used to convert a Fordson tractor into a screw-propelled vehicle with a single pair of cylinders. A machine used in the Truckee,CA area was referred to by locals as the "Snow Devil" and that name has been erroneously attached to these machines, although no known advertising of the time referred to them as such. A film was made to show the capabilities of the vehicle as well as a Chevrolet car fitted with an Armstead Snow Motor. The film clearly shows that the vehicle copes well in snow. Steering was effected by having each cylinder receive power from a separate clutch which, depending on the position of the steering gear, engages and disengages; this results in a vehicle that is relatively maneuverable. The promotional film shows the Armstead snow motor hauling 20 tons of logs. In January 1926, Time magazine reported: An extant example is in the collection of the Hays Antique Truck Museum in Woodland, California. This particular vehicle is said to have been used to haul mail from Truckee to North Lake Tahoe. The Second World War period With the occupation of Norway by Nazi Germany in World War II, the quixotic Geoffrey Pyke considered the problem of transporting soldiers rapidly over snow. He proposed the development of a screw-propelled vehicle based on the Armstead snow motor. Pyke envisaged that the vehicles would be used by a small force of highly mobile soldiers. The damage and casualties that a small force could inflict might be slight, but they would oblige the enemy to keep many men stationed in Norway in