The British army is bound by His Majesty's Rules and Regulations to play at the Philharmonic pitch, and a fork tuned to a' 452.5 in 1890 is preserved as the standard for the Military Training School at Kneller Hall.
A frequent combination was flute, violin and harpsichord (very probably with a violoncello doubling the bass), and in more than one case the violin was partly tuned lower to soften its tone.
Stein tuned Mozart's piano to a fork a' 421.6, and the Broadwood pianos used at the London Philharmonic Society in its first concerts (1813) were tuned to a fork c 2 506.8, which gives a mean tone a' 423.7.
Johann Heinrich Scheibler (1777-1838) tuned two forks to an exact octave, and then prepared a number of others dividing the octave into such small steps that the beats between each and the next could be counted easily.
But a cardboard tube closed at one end, with the open end near the ear, will often suffice, and it may be tuned by more or less covering up the open end.