in a serious manner; "talking earnestly with his son"; "she started studying snakes in earnest"; "a play dealing seriously with the question of divorce" Scrapingweb Dictionary DB
I was just telling Mr. Lester that I didn't mind that, said Swain earnestly that I could stand anything, if I was only sure that Miss Vaughan was safe. – The Gloved Hand by Burton E. Stevenson
" We ought to go at once," she said earnestly – A Little Maid of Old Maine by Alice Turner Curtis