I dug around & found it described as Johnston Harvester Continental Disk Pulverizer Agriculture Machinery, made in Batavia, NY. As a gal from a farm state, I know perfectly well that the ground has to be broken up in order to plant. Hence, a pulverizer.
I was wondering if Lath might be an abbreviation for Lithographer & quickly found this: George S. Harris, born 1823 in Bridgeton, NJ, worked in Philadelphia as a lithographic and letterpress printer, producing lithographic trade cards, can and cigar box labels, circulars, calendars and stamped envelopes between 1847 and 1891. By the end of the 1880s the company (with three sons as partners) operated the largest lithographic firm in Philadelphia, with 600 employees.
I love that I can find answers to pretty much any idle inquiry, but sometimes I miss trying, trying, trying to remember the next line of a song, conferring with friends, or simply wondering what this or that means. As I still do about this ad, even knowing the particulars.