(the anonymous translation of Castel's essay of 1735) is located in the British Museum. The envelope that contains the pamphlet has a handwritten note signed by M. Low, the first owner:
I was admitted among a select party to a sight of [this instrument] at the Great Concert Room in Soho Square; but to a sight of the instrument only, for nothing was then performed nor afterwards, as ever I heard, neither did I ever know why [13].
In spite of this, there is no question that the interesting experiments of Father Castel were directly responsible for the development of other theories and instruments in the first half of the nineteenth century. Although these yielded no lasting results, they led to later innovations that initiated our own audiovisual age.