Figure 37. Bucknill-Casella manometric sounder, invented by Lieutenant John T. Bucknill of the Royal Engineers of the Royal Navy in 1870 to mitigate problems with existing sounding systems. This sounder was based on Bourdon’s tube, whose curvature varied as a function of the pressure difference between the interior and the fluid in which it was immersed. Louis P. Casella made the final product.
Photo Category: Oceanography - Historical instruments