add charcoal to the fire/replenish the fire with charcoal
すみ【隅】
〔囲まれた部分の角〕a corner;《文》 a nook
私は写真の左下の隅にいます
You can see me in the lower left-hand corner of the picture.
いつも隅に引っ込んでいてはだめよ
Don't just hide [stay] in the corner all the time.
隅から隅まで捜したのか
Have you 「looked everywhere [searched every nook and cranny]?
そのことを隅から隅まで知っている
I know it like 「a book [the back of my hand]./I know every detail of it.
あんな美人の彼女がいるなんてあの男も隅に置けないな
He must know a thing or two to have such a good-looking girlfriend./There must be more to him than 「meets the eye [we think] if he has such an attractive girlfriend.
すみ【墨】
1〔墨汁〕India(n) ink, Chinese ink;〔固形のもの〕sumi, an ink stick
墨をする
rub an ink stick back and forth on an ink stone (to make ink)