[R] defining columns in a matrix

[Kindra Martinenko]

Hi all,
I have the following 7 x 7 matrix.  I am trying to figure out how to
label the columns to something more descriptive other than [,1], [,2],
etc.
I have tried the c(x,y,z,) function, but I get a error returned
stating that my vectors need to be the same length.  Do I need to
convert this to something else such as a list and then repack it?

Thanks,
Kindra

         Volume
Time        [,1] [,2] [,3] [,4] [,5] [,6] [,7]
  17:00:00 7146 4926 5394 4534 6273 6192 6189
  17:10:00 7227 4851 5414 4620 6026 7159 5878
  17:20:00 7477 4678 5502 4298 6516 6469 5631
  17:30:00 6533 4608 4813 4212 6083 5837 5657
  17:40:00 6355 4669 5106 4242 5717 5635 5282
  17:50:00 5657 4472 4545 3860 5378 4804 5304
  18:00:00 5338 4508 4273 4024 4666 4597 5162