A large eccentricity also produces an unsymmetrical light variation, the minimum occurring at a time not midway between two maxima; stars of this character are called Cepheid variables, after the typical star S Cephei.
Indeed, some of the chief contrasts of the two continents arise not so much from geological unlikeness as from their unsymmetrical situation with respect to the equator, whereby the northern one lies mostly in the temperate zone, while the southern one lies mostly in the torrid zone.
The main effects we have to discuss are (I) a symmetrical widening, (2) a shift of wave-length, which when it accompanies expansion in both directions may appear as an unsymmetrical widening, (3) a change in the relative intensities of the lines.
The agora is of unsymmetrical form; its sides are bordered by porticoes, interrupted by streets, like the primitive agora of Elis as described by Pausanias, and unlike the regular agoras of Ionic type.
The limbs are stout and short, terminating in unsymmetrical hoofs, the external being rounded, the internal pointed, and the sole partially covered with hair.
The unsymmetrical form of the meridional pencil - formerly the only one considered - is coma in the narrower sense only; other errors of coma have been treated by A.
The most famous is the first, which is doubly misnamed, since it is not a temple and its contour is too unsymmetrical to be described properly as elliptical.
The lines are broadened (as was already known), the intensity of emission is much increased, but some are weakened and some strengthened, nor is the amount of broadening the same for all lines, nor is it always symmetrical, being sometimes greater on the red side; but besides the effect of unsymmetrical broadening, every line is displaced towards the red; different lines again behave differently, and they may be arranged somewhat roughly in a few groups according to their behaviour; reversals are also effected, and the reversed line does not always correspond with the most intense part of the emission line.
Thiourea and many of its unsymmetrical derivatives have marked physiological action; thiourea causes a slowing of the pulse and respiration, cardiac failure, and death in convulsions; phenyl-, ethyland acetyl-thiourea are actively toxic. The most important derivative pharmacologically is allyl-thiourea, also known as thiosinamine or rhodallin, NH2 CS NH CH2 CH:CH2.
CH: CH 2; isopropylethylene, (CH 3) 2 CH CH: CH 2; symmetrical methyl-ethyl-ethylene, CH 3 CH: CH C 2 H 5; unsymmetrical methyl-ethyl-ethylene, (CH 3)(C 2 H 5)C:CH 2 i and trimethyl ethylene, (CH3)2C:CH(CH3).