flatways

flat·wise

 (flăt′wīz′) also flat·ways (-wāz′)
adv.
With the flat side down or in contact with a surface.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

flatways

(ˈflætˌweɪz) or

flatwise

adv
with the flat or broad side down or in contact with another surface
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in classic literature ?
So he sweated and fired up and watched the glass fear- fully (with an impromptu charm, made of rags, tied to his arm, and a piece of polished bone, as big as a watch, stuck flatways through his lower lip), while the wooded banks slipped past us slowly, the short noise was left behind, the interminable miles of silence--and we crept on, towards Kurtz.
A contemporary book on Northamptonshire stated: "Rants Ragg, a stone very much esteemed in this county contains a beautiful variety of shells' they usually lye flatways in the bed.
You seem to me to be altogether out in the Territory and free to whip and turn and pile up flatways and jump anywhere take off disappear make hay anything damn thing you or anybody else might want to