Size Variation of Repeated Objects in Period Armorie
Recently I submitted the arms seen here to the Tir Righ College of Heralds and it has (as of this writing) been passed to Laurel for comment and a final decision. One question that came up more than once in the process was, why are the cannons different sizes? The blazon submitted was: Per pale sable and gules, in fess three cannon barrels palewise argent
Notice there is no mention of the varying size of the cannons. The arrangement is specified as, of course, is the colour (argent = silver or white) but it does not say that the middle one should be bigger.
I made it thusly for purely aesthetic reasons in that I thought it filled the space batter. Many years ago when Baron Gerhard Kendal taught me the basics of heraldry he instilled in me an appreciation of what he probably called (at least I assume that's where I picked it up) the heraldic sensibility. A way of seeing art and the layout of images that was ever so slightly different than our modern sensibilities often prefer.
I found some examples of devices drawn in period in a book from 1572: Workes of armorie by John Bossewell. Both examples show three objects with one being drawn slightly larger to fill the space better. The columns are arranged identically to my cannons with the middle drawn slightly larger to correspond with the longest dimension of the shield shape. The candlesticks are arranged to fit around a chevron. Notice the Chevron leaves a bigger space at the bottom so the artist has made that candlestick slightly larger.
I believe there is no reason to specify this, for if these devices were drawn on a square shape (ie a banner) the three objects could be drawn the same size to better balance the spaces available.