SYP]                              NAUTICAL  DICTIONARY.

* Suppose the temperature observed by the mercurial thermo¬
meter to be 52° 4', then slide the sympiesometer scale until the
pointer is at 52° 4^ on the fixed scale, at the right hand side under
the sliding scale; it is to be observed that the numbers on this
scale, and also on the thermometer, read downwards, and the top
of the column of red fluid stands opposite to the second division
above the third-tenth higher than the number 30. The height of
the barometer is then 30 inches y^ and ^wu ^^ ^^ inch, or 30-34
inches. The tenths are easily distinguished from the hundredth
parts, by the lines being drawn longer. As it is convenient to
know what change has taken place since the last observation, the
circular register at the bottom of the frame should be set, by
turning the division on it corresponding to that indicated by the
sympiesometer to the fleur-de-luce or index. When the column
of fluid descends, bad weather may be expected, and when it rises
the weather will in general be fine.'

A veteran naval officer, who has supplied much useful infor¬
mation for the present edition of this Dictionary, states that he
worked one of the first sympiesometers which Mr. Adie made,
and saved himself from many a gale by following its indications;
and he considers that no ship ought to be without one. Many
seamen think that this instrument is too sensitive, and sometimes
alarms the mariner unnecessarily. In France, M. Gaudin has
endeavoured to render it still more sensitive in its action.

SYPHERED, implies a mode in which two planks are joined
together with bevelled ends.    The same as Mitred.

T-PLATES, in Shipbuilding, are plates of iron in the form of
the letter t they are used for various purposes.

TABLE LAND. Flat country. A long tract of land, flat
on the top,

TABLE MONEY. An allowance to flag officers, &c., in
addition to their pay, to meet the necessary expenses of their
mess-tables.

TABLING, in Shipbuilding, letting one piece of timber into
another by alternate recesses and projections on each, to prevent
the pieces from drawing asunder or slipping upon one another.
See also Dowells,

TACK (Fr, Virer de bord). To put a vessel about; that is,
to change her course from one board to another by bringing her
head up to the wind, putting the helm a-lee till the wind bear
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