870 REPORT— 1900. 



Vhich was riveted to a cylinder of a small steam engine •which acted as A dash* 

 pot. The ports of the steam cylinder were closed up, and a small hole drilled 

 into the piston was found quite sufficient when the cylinder was filled with oil to 

 check the free oscillations of the spring. 



Speed Indicator. — The speed indicator was a Schaffer and Budenburg tacho- 

 meter to which a temporary wooden wheel was attached, and a special dial was 

 made, so that instead of indicating revolutions per minute the miles per hour at 

 which the vehicle was travelling were at once made visible. The mode of con- 

 ducting the experiments is shown by a photograph. A rope about 20 feet long 

 was attached to the Voiturette and connected with the dynamometer, the dial of 

 which an observer was able to read. At the same time a second observer called 

 out the actual speed of the vehicle at that instant and the nature of the road 

 which was being passed over, which were recorded by the first observer in his 

 notebook, together with the pull on the dynamometer. 



The net result of the experiments showed that, even on apparently the 

 smoothest road, the variation in the pull was so considerable that nothing but 

 appliances which would record autographically both the pull and velocity at the 

 same instant and indicate also the distance travelled, so as to identify the exact 

 piece of road corresponding to the record, would be of any value. Moreover, it was 

 evident that some autographic record of the nature of the road, as well as some 

 instrument for recording the vibration of the vehicle which was being towed, was 

 necessary in order to form some estimate of the effect of vibration upon the resist- 

 ance. With such appliances the pull on waggons, lorries, ordinary vehicles with 

 iron rims, pneumatic and indiarubber tyres, could be investigated for any speed, 

 and it is not too much to hope that some definite idea of the laws concerning 

 traction might be found, with the eflect of springs, tyres, and the surface of the 

 road taken into account. 



2. The Viagraph. By J. Brown. 



The viagraph is an instrument for indicating the degree of unevenness of road 

 surfaces, and consists in principle of a straight edge to be drawn along the road 

 surface and provided with a profiling wheel running on the surface, the vertical 

 motions of which are transmitted to a pencil marking on a paper band, drawn 

 under its point by a drum revolved by gear connected to the profiling wheel. The 

 result is a profile of the road surface full size vertically, and \ inch to 1 foot 

 horizontally. Means are provided for indicating the sum of the vertical motions 

 of the profiling wheel, which sum represents numerically the relative unevenness 

 of the road, and is called the index of unevenness when taken for a unit length of 

 88 yards of road. This length is automatically measured by the instrument, and 

 an alarm bell rung when it has been traversed. Speculations as to the causes of 

 unevenness, the proper make of wheels and springs for a given unevenness, and 

 calculations of the horse-power absorbed in traction due to unevenness may be 

 founded on the indications of the instrument. 



3. A Self-registering Rain-gauge. By W. J. E. Binnie. 



This rain-gauge is constructed so as to register the rate of rainfall at any 

 moment by means of the drops falling into the interior of the gauge from the 

 orifice of the collecting funnel. 



The weight of each drop depends upon — 



1. The surface tension between air and water. 



2. The dimensions of the orifice. 



3. The interval which .separates the fall of the drops. 



1. The surface tension varies with the temperature, amounting to about xaVir 

 per degree Fahr , giving a probable maximum error of 2^ per cent. 



3. The influence on the size of the drops of the interval between the fall of 



