Complex sentence: In 1687 Bombay was placed at the head of all the Company's possessions in India; but in 1753 the government of Bombay became subordinate to that of Calcutta.
Split into simpler sentences: In 1687 Bombay was placed at the head of all the Company's possessions in India. However, in 1753 the governor of Bombay became subordinate to that of Calcutta.