Digging the Footings

The barn is 24 feet long by 20 feet wide. First I had 3 truck loads of 3/4 inch aggregate delivered and spread to raise and level the barn floor. (For good info on proper horse footing see http://pubs.cas.psu.edu/freepubs/pdfs/ub038.pdf).
I dug all nine footings by hand. Each hole was 2 feet by 2 feet and 4 feet deep.

In New Hampshire the ground can be very chunky. Rocks of all sizes were compacted into the clay by the glaciers during the ice age. I used a pry bar, coal shovel, spade, pick axe, post hole digger, a bucket, chains and ropes. It took me three months because the rains came and filled all the holes to the brim after only fve were dug. I had to pump the water out of the holes which would refill overnight
I bought BF24 bigfoot footing forms http://www.bigfootsystems.com/ for the footings onto which the 10 inch sonotubes were attached. After having the 48 inch deep holes inspected by the town, I positioned the footing forms with sonotubes in the holes, back filled them with dirt. pumped out the water, and poured the cement ( one bag dry, two mixed)