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Maillefert

Is the Loud Diving Bell a Maillefert Design?

by Manuel B. Carvalho

It has been suggested that the Loud Diving Bell is a Maillefert design.  This is unlikely to be the case because the designs are so different.  

Benjamin Maillefert was an engineer for the NY Submarine Engineering Company who was well known for his underwater blastin
g in Hell Gate conducted in order to improve navigation.  This work went on around the time P. H. Loud was living in Staten Island and Loud would have undoubtedly heard of his work since it was well reported at the time.  Maillefert patented a diving bell in 1858 whose major improvement was an air reservoir that was used to move the diving bell.  His invention however differed significantly in design from Loud's 1875 bell and his 1883 patent, which Loud called a floating caisson, in these main points:


Diving Bell design comparison

  • 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.


Modified wording under ballast to better differentiate design differences: 23 Nov 2012.
Added links to patents: 19 Nov 2012
Original document posted:  15 Apr 2012.