| 摘要 |
<p>The tide calculating allows the relationship between time of day and height of marine tides to be used to determine any one parameter given the others. A rectangular plexiglass sheet (1) has a set of lines (7) radiating from a single point at one end of the sheet, characterised by their relative positioning based on the 'twelfths' rule of tidal rise and fall. A perpendicular scale (6) slides along a longitudinal slot (3) which allows the usual tide height in the region to be set against the 'maximum tide' radial line (7). At the opposite end of the plexiglass sheet (1) a rotating circular scale (5), with its periphery having a scale divided into hours and minutes, has its centre movable in a slot in the plexiglass sheet (1) so that the times of high and low tides may be set against radiating lines meeting the tide lines. A clamp screw holds both moving components once positioned in their slots.</p> |
