SHERLOCK HOLMES OF THE FORESTS 



75 



tomobiles by merely examining the tire tracks. On earth 

 roads, the pattern imprint of non-skid tires is steeper 

 and more distinct on the rear side of each indentation 

 while stones are shoved ahead by the wheels, the paths 



SHOES WORN HEEL FOREMOST 



It took a microscope to detect the clever effort of an incendiary 

 to throw detectives off his track by wearing shoes heel foremost 

 but the trackers were not fooled. Depressions in the tracks 

 excited their curiosity and they quickly solved the mystery and 

 got their man. 



of these stones usually being intact close behind where 

 they stop while dust is piled up by their shove on the for- 

 ward sides. The imprint of partly imbedded stones, 

 slightly displaced by the wheels also furnish evidence of 

 machine direction, the displacement being backward in 

 very small stones, and forward in those large enough 

 to receive both lateral and downward pressure. A sprink- 

 ling of sand or dust usually is deposited on the rear 

 side of stones or other obstructions passed over by the 

 wheels while the forward side is usually swept clean. 

 In dropping into chuck holes, the impact, or wider tire 

 imprint, is greater on the forward side of the hole or 

 against the obstruction. In dropping into ruts, a wheel 

 will run on the high side to a feather edge, while in 

 climbing out, it will remain in the rut until side pres- 

 sure forces it to climb out abruptly. Other landmarks of 

 automobile direction are: the direction in which water 

 drops or mud are carried out of a mud hole, traction 

 slips which occur in going up steep grades, the turn on 

 curves which usually is more abrupt on leaving than on 

 entering the curve and the "Y" where a machine backs 

 out of a roadside stop. 



Excessive speed generally is evidenced by the wind swirl 

 disturbances of the track, the distance of the side throw 

 of mud, sand or water, side lurch on rough roads and 

 the distance of the wheel jump in passing over obstruc- 

 tions. The size of the car is indicated approximately by 



the width of the tire tread although this is affected by the 

 amount of load and the air pressure of the tires. When 

 the load is heavy, there is a higher piling up of the dust 

 ridge which is left in the center of the wheel track by 

 suction and thrust of traction on pneumatic tires. 



Under conditions where it is not feasible to dig out 

 the footprint itself or to make a cast of it, the usual plan 

 pursued is to photograph the track. In such case, the 

 camera lens is placed exactly parallel to the surface to 

 be photographed, to avoid distortion of perspective. A 

 special clamp is used for attaching the camera to a board 

 or support set up at the required angle. Thereafter, the 

 photograph can be enlarged to the exact size of the origi- 



HOB-NAIL TRACKS 



Impressions from a peculiar kind of hob-nail in a shoe led the 

 tracker to discover a shoemaker who remembered putting them 

 in a man's shoes. The man was arrested and found guilty of 

 firing a forest. 



nal foot print. In cases where a camera is not available, 

 the watchmen of the forest draw accurate diagrams of the 

 tracks on paper and henceforward use them as identi- 

 fication indexes. 



Finger print records are made permanent by sprink- 

 ling some powder of contrasting color such as aluminum 

 or bronze over the prints. Dragon's blood powder for 

 light surfaces and talcum powder or gray chalk for dark 

 surfaces are very satisfactory. Where these materials 

 are not available, powdered charcoal, or very fine pencil 

 scrapings can be used over light surfaces and borax or 

 flour for dark surface's. All these materials must be dry 

 when used as they pile up and are generally unsatisfac- 

 tory for such purposes when damp. Subsequently, these 

 finger prints which are smudged easily by friction, may 

 be set by spraying lightly with a solution of one part of 

 white shellac and four parts of wood alcohol. Dragon's 

 blood can be set merely by heating slightly with a match 

 flame after being applied to the surface where the finger- 

 print occurred. 



