TOWER n.
t.), a bastion of masonry, often with chambers beneath, built at an angle of the interior polygon of some works. -- Tower mustard (Bot.), the cruciferous plant Arabis perfoliata. -- Tower of London, a collection of buildings in the eastern part of London, formerly containing a state prison, and now used as an arsenal…
TRIMORPHISM n.
f having three different shapes or proportions of corresponding parts; -- contrasted with polymorphism, and dimorphism. Heterogonous trimporphism (Bot.), that condition in which flowers of plants of the same species have three different lengths of stamens, short, medium, and long, the blossoms of one individual plant h…
TWINNING n.
complished for example by pressure), the process by which this reversal is brought about. Polysynthetic twinning, repeated twinning of crystal lamellæ, as that of the triclinic feldspars. -- Repeated twinning, twinning of more than two crystals, or parts of crystals. -- Twinning axis, Twinning plane. See the Note und…
ULTRAMARINE n.
ther silica, alumina, soda, and sulphur, thus forming a glass, colored blue by the sodium polysulphides made in the fusion. Also used adjectively. Green ultramarine, a green pigment obtained as a first product in the manufacture of ultramarine, into which it is changed by subsequent treatment. -- Ultramarine ash or as…