30 MEDICAL JURISPRUDENCE The crowns of the temporary teeth are of a white china-like colour and are marked with a ridge or thick edge at their junction with the fangs; while the crowns of the permanent teeth are ivory white and have no ridge. The anterior temporary teeth are vertical, and the permanent teeth are usually inclined a little forward. Height and Weight.—A full-term child at birth is, on an average, 19 to 20 inches in length and 6 to 7 pounds in weight. It is generally 24 inches in length at the age of the sixth month and 27 inches at the end of the first year. At the end of the fourth year it is, on an average, double its length at birth. If the health and nutrition are maintained, the child gains in weight nearly one pound a month during the first year, so that it is generally double its birth-weight at the end of the fifth month, and treble its birth- weight at the end of the first year. But the progressive increase in height and weight according to age varies so greatly in individuals that it cannot be depended upon in estimating age in medico-legal cases. Ossification of Bones.—This sign is helpful for determining age until ossification is completed, for skiagraphy has now made it possible to deter- mine even in living persons the extent of ossification, and the union of epiphyses in bones. Owing to the variations in climatic, dietetic, hereditary and other factors affecting the people of the different provinces of India it cannot be reasonably expected to formulate a uniform standard for the determination of the age of the union of epiphyses for the whole of India. However, from investigations carried out in certain provinces it has been concluded that the age at which the union of epiphyses takes place in Indians is about 2 to 3 years in advance of the age incidence in Europeans and that the epiphysial union occurs in females somewhat earlier than in males. Fig. 7.—X-Ray photograph of the elbow of a boy, aged 15 years and 8 months: Epicondyles not united with the lower end of the hume- rus and olecranon not united with the body of the ulna. Fig. 8.—-X-Ray photograph of the elbow of a girl, aged 15 years and 10 months: Epicondyles united with the lower end of the hume- rus but the olecranon is not united with the body of the ulna.