fixtures for trade

The general rule of the common law certainly is, that whatever is once annexed to the freehold becomes part of it, and cannot afterwards be removed, except by him who is entitled to the inheritance. The rule, however, never was, at least as far back as we can trace it in the books, inflexible, and without exceptions... But an exception of a much broader cast, and whose origin may be traced almost as high as the rule itself, is of fixtures erected for the purposes of trade. Upon principles of public policy, and to encourage trade and manufactures, fixtures which were erected to carry on such business, were allowed to be removed by the tenant during his term, and were deemed personalty for many other purposes.