This triangle is from 1902 Butterick Publishing’s Fancy and Practical Knitting, p. 86, no. 7. It’s the top half of the “Knitted Tidy” square. The bottom half of this square is already on Ravelry: “Rosedale Counterpane/Apricot Leaf Square” and “Bedspread (Counterpane w/Leaves)”. Neither pattern includes this top half. This pattern will also work by itself with any even number of cast-on stitches. I recommend casting on over 36 stitches for at least 2 pattern repeats. Tidy Triangle has 18 pattern rows: 3 eyelet rows and, except for the first 3 stitches, 15 knit-across or purl-across rows. It knits up faster and faster as you near the point!
The sample is 8 inches on its short sides and 11 inches on its longest side.

Skills needed: cast on, knit, purl, YO, k2tog and k3tog.

Gauge is not important in this pattern. Any block-able yarn/thread will work. Make a swatch to check gauge and appearance.