Louis Paschal Casella was born in Edinburgh in 1812. Later moving to London, like many of the Italian immigrants who settled in the Holborn and Clerken-well area he was skilled as an optical glass maker and barometer and thermometer maker. The Tagliabues were an even longer established firm of philosophical instrument makers, and in 1838 Loius Casella joined as co-partner to Caesar Tagliabue at 23 Hatton Garden. By 1844 they described themselves as "Opticians and philosophical and mathematical instrument makers and mathematical instrument makers, drawing instrument, hydrometer and saccharometer, burometer, thermometer and telescope makers".
Louis Casella and Co. superceded Tagliabue and Casella in 1848, and the Company expanded dramatically. They became instrument makers to the Admiralty and the Government of North America in 1856, and to the East India Company and the Board of Trade in 1860.
The Company both fed on and catered for the scientific advances of the nineteenth century, manufacturing individual's patented inventions, and providing the increasingly sophisticated measuring instruments required for further research.
The Company was based at Britannia Walk, Shoreditch at the time of the deposit in 1982.