A roasting jack is a mechanism that turns a spit, usually over an open fire or fireplace. These could be or are still mechanical in nature, or they could be simple hand cranked devices that were extremely labor intensive. Most cooks will tell you that spit roasts are best when the meat is turned in a rotisserie like style, constantly and slowly, providing even heating to all sides.
While we often think of the spit as horizontal across a fire, some of the earliest and simple roasting jacks were homemade. Meat was placed on a string, which was then attached to a metal fixture at the top of the fireplace. This hung the meat vertically, and merely required the cook to occasionally flick the meat to keep it spinning. This would have created uneven cooking, because the top of the roast would not have been as heated as the bottom. Horizontal spits might have handles that would be hand cranked by cooks, children, housewives or other household workers to produce roasted meat.
Mechanized roasting jacks began to emerge during the 18th century. Many worked upon the same principal as a clock, and needed to be wound up several times to create the spin needed. Alternately, some worked not in wind up fashion but instead used a series of weights, like authentic cuckoo clocks, which allowed mechanized spinning of the meat. If the meat stopped turning, the weights were readjusted to keep the spinning going.
The roasting jack was often built onto fireplaces, and some fireplaces had spacious areas underneath logs where drippings could be collected. Granted, these might contain some ash too, but they might be saved and reused or discarded. Fireplaces of today tend to be much smaller and usually don’t have the height and depth needed to provide ample space for a roasting jack. If you have the good fortune to live in a home dating back to the 19th century, you may very well have a fireplace ample enough to try cooking on the hearth.
Though most roasting jacks worked on wind up and weight mechanisms, electricity brought with it less use of fireplaces for cooking, and other means to spin meat. Huge rotisserie ovens existed before electricity had become commonplace, and these roasting jack styles tended to operate like wind up toys. The winding up process took a long time, because some early rotisseries style ovens could cook numerous roasts at the same time. Some were designed to cook well over 100 roasts at once.
A roasting jack of today is often an unseen mechanism, usually imbedded in a rotisserie oven. There are also some electric powered turners connected to conveyer belts, used for turning spitted meat over open fires. Whole pig roasts are now often cooked with these turners, and most rave at the results.