| 摘要 |
Device intended to give out a warning signal at the first appearance of snowfall. The invention comprises a light source giving out approximately parallel rays 1 which light up the non-reflecting control target 6 and a photosensitive cell 3 directed towards the said target and supplying an electrical signal as soon as the said target 6 receives falling snow which reflects the light given out by the source 1 towards the cell 3, which signal, when amplified, enables a warning to be transmitted over a long distance. The invention may be used for detecting any snowfall as soon as it starts on roads, in order to enable them to be immediately cleared so as to keep them passable at all times. <IMAGE>
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