Maillefert

• Ballast

Maillefert's design on the left uses a compressed air tank that is filled with water for ballast or emptied with compressed air in order to lower or raise the bell. Loud's design however uses an open topped ballast chamber, rather than a tank, that is intended to be filled with solid material such as sand or rocks.

• Shape

Maillefert's design of the working chamber is conical in shape compared to Loud's rectangular's design. Additionally, Loud's Bell has a wedge to break river currents and Maillefert's design does not but is rather a basic circular shape.

• Size

The NY Submarine Engineering Company offered Maillefert's design for sale in four different sizes. For example, in a 1860 prospectus, the company offered a 1,000 foot cubic foot bell for $3,200 and a 500 cubic foot one for $2,600. Loud's bell is just under 600 cubic feet which is not a size made available by the company.

Additionally, it's unlikely that Maillefert had time to help Loud with his diving bell. In 1874 Maillefert was very busy in Charleston Harbor in South Carolina salvaging the many Civil War wrecks there. His work there involved blasting the wrecks and then lifting up the pieces without the use of diving bells. Unfortunately by 1876 he was bankrupt, desperate for money and his health took a turn for the worst. Significantly, Loud makes no reference of the Maillefert design in his patent which infers this was a Loud invention independent of Maillefert. No available documentation suggests that there is any connection between Loud and Maillefert.

Since they are both diving bells there are, of course, similarities in the design. However, because of these major differences it's unlikely that Maillefert designed and built Loud's diving bell.

It's not known who designed and fabricated Loud's Diving Bell but it seems improbable that Benjamin Maillefert was involved.