The Dahlgren Projectile;

[John D. Bartleson Jr.]

To All Interested;
     Pete George's revised edition of his book aptly summarizes the patent awarded to John A. Dahlgren so I will not go into its make up here.  You  can google the patent number below to read all about them.
      One thing not discussed in the patent is the use of the copper or brass stud (rivet) found in the nose of the so called 'blind' shell.  Blind meaning inert by modern use.
        Two models of the English Whitworth projectiles use a brass or copper stud in its nose to help transmit the heat of penetration to the black powder filler, thus no fuze is required.
         I have often thought why Dahlgren didn't use a cast iron plug?  It would have been harder than the copper one and certainly cheaper to make.  Is it possible it was also intended to be used as a hollow, heat detonated shell?  The patent states it was to be used as a solid shot.  In that event the hollow chamber would have been used to reduce weight and thus reduce stress on the gun.
       Just a thought to ponder.  Oh, has anyone analyzed the 'black sand'?
      Ever wonder why only one or two fuzes especially made for the threaded Dahlgren shell have been recovered?  Are they all in the ocean?? what fuzes have been used then?
So many blind shells, so few fuzed ones - very strange.
Regards,
John
Patent No. 32,986, dated August 6, 1861
 Double click the images to enlarge.

[Jack Wells]

Many years (51 or 52) ago a friend and I sectioned two (2) of the 12 Pdr. (3.4") fired shells we had found,and both had black "Casting Sand". That it was "Casting Sand",was confirmed by three(3) different people that were involved in metal (Iron,Brass) casting.The Copper/Brass Rivet,one of @ in the projectiles we sectioned,perhaps  to hold and center the Core during casting? Light Wt High velocity concept ?
Jack

[Jack Wells]

Should have typed,both were filled with "Black Casting Sand"
Jack

[John D. Bartleson Jr.]

Jack,
When you sectioned these shells did you see anything opposite the stud that might have supported the other end of the sand core?
 I think a suport made of brass or copper would have melted away in the molten iron.
John

[Jack Wells]

No,we cleaned the insides with diluted muriatic acid,and there was no sign of any form  of (Iron) centering post in the base,which we thought was odd.I agree about the Brass/Copper rivet as a centering post melting when the shell was cast around it.
Jack