The Act shall apply to every Institution for the Time being established for the Promotion of Science, Literature, the Fine Arts, for Adult Instruction, the Diffusion of useful Knowledge, the Foundation or Maintenance of Libraries or Reading Rooms for general Use among the Members or open to the Public, of Public Museums and Galleries of Paintings and other Works of Art, Collections of Natural History, Mechanical and Philosophical Inventions, Instruments, or Designs ; provided, that the Royal Institution, and the London Institution for the Advancement of Literature and the Diffusion of useful Knowledge, shall be exempt from the Operation of this Act.