| 摘要 |
The timer comprises an air-tight tube (11) filled with a fluid and a mobile mark such as a ball or a bubble (12). The density of the fluid and the mark are chosen so that the position of the mark, moving due to gravity, indicates the elapsed time. Graduations or marks along the tube are used to indicate these times. - The device is fitted with a rubber support with a slot so that it can be inserted in the alternative positions needed for the mark to fall. This timer is useful, for example, to indicate that a mixed glue is ready for use or that one has brushed one's teeth for a sufficient time etc.(3/4)
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