A fantastic find indeed!
Bushby's drawing technique, first a pencil passage and later the pen is efficient and fun to observe.
More than merely efficient :: ART !
See esp. v3:265 [pdf #s] (last pg.), 264
&
v3:136 has even graceful crossing out of upper-left
text, and then many pp. of "pointing" fine illustrations.
v4:180 & around are some nice closed-curve/topological
knots (and somewherElse there is a dense presentation
of maybe Tait's? knots that has such grace of pen).
(-;