proceedings

Applications of Punched Card Equipment
at the Naval Proving Ground
I WAN T to make a few remarks about some of the
computations that we have undertaken at the Naval Proving
Ground. We are responsible to the Bureau of Ordnance
for a good deal of ballistic computation work: the production
.of firing tables for guns, rockets, and projectiles.
Our department covers other agenda, but I will speak
merely of our computation work.
We have at the Proving Ground a set of the usual IBM
machines, including the collator, the Type 601 and the
Type 405, of which much has been said. We put in those
machines as soon as IBM w.ould furnish them to us after
a conference that I had with Dr .. Eckert at the Naval Observatory.
I think that must have been back in 1943. We
found them very useful, particularly at times when our
manpower was very short, and our work load was very
large. Sometimes we were operating under a contract
with MIT, so that we had the output of their differential
analyzer. We t.ook the output of the differential analyzer
and digested the results at the Proving Ground. A great
deal of our processing was done on the IBM machinery.
Our ideal has been to produce range tables with very
little being touched by human hands. Weare far from
that ideal at the present time. We think that in time we
will approach that with our IBM machines and our
Mark II Calculator as well as our battery of desk type
machines. A point that I think should be made in connection
with any computation laboratory is that you need a
certain balance and that one type .of machine does not in
general render the other types unnecessary.
In addition to the machines that I have mentioned, we
have one of the IBM Relay Calculators, .of which five
have been manufactured. Two are at Aberdeen Proving
Ground, and I believe two are at the Watson Laboratory.
I am not sure whether any more have been manufactured.
We have just one of them, and we have put it to considerable
use.
Among the vari.ous projects that we have carried out on
this piece of apparatus has been the computation of sine
functions to seventeen significant figures for each ten min-
CLINTON c. BRAMBLE
u. S. Naval Proving Ground
99
utes of arc. This was done for a special purpose as we
were about to do a job for which the m.ost appropriate
table did not seem immediately available. We have also
for our own purposes calculated tables of ere and e- re to
eighteen significant figures. We have also prepared density
log tables for our .own use, and we have done a great deal
of auxiliary work in connection with production of range
tables. The 601 has been particularly useful in the calculation
of bombing tables inasmuch as these tables are
produced by four term interpolation f.ormulas from a general
ballistic table. Among other projects that we have
carried through have been the reductions of field observations
of flight of bombs; we have reduced the work a go.od
deal so that we are now in the process of eliminating
graphic procedures almost entirely.
To return to the IBM Relay Calculator, we have calculated
a number of soluti.ons of a differential equation, a
special case of the type that was discussed twice yesterday.
Our special formula involved the calculation of the particular
solution of the differential equation, and was especially
concerned with the determination of a parameter in
the equation so that the soluti.on would fit a given condition.
One other piece of apparatus I should mention we have:
a card-operated typewriter in which the keyboard was set
up for our own special purpose. I have with me a copy of
a density table which was made by the use of duplimat
papers in the typewriter and directly produced from the
duplimat; this is a very nice job. The heading, of course,
was typed with another typewriter.
By the use of our accounting machine, range tables are
also printed on specially preprinted forms. \Ve not only
print .on the 405, but also use it for differencing purposes.
On this density table there is a sample of six differences
so produced. We can, by use of a properly set up
control panel, run off the cards which contain the data on
our range tables, select any two columns and get first, second,
and third differences simultaneously. \Ve use this as
our check process and we find it very satisfactory. Various