[Migara]

The most likelihood is that Barnes bowled two kinds of deliveries off two grips. First one is the orthodox seamer. Since he was a strong man, would have been fast medium with the pace. Other one would have been the leg roller, which is rolled of the back of the hand to get some spin, but bowled with a medium pacers action (poor man's example is Chris Harris). Now this would have been lot slower than his seamer, but it's still possible to be little quicker than an orthodox spinner. Any batsman of substance, would have been able to pick the difference of pace if Barnes bowled the former in high pace. Being a shrewd operator, he would have bowled his seamers little slower, so the change of speed is not apparent. With new ball, he must have bowled close to full speed with swing and seam, with one or two leg rollers to intervene. When ball got older he would have gone to leg roller mode, and with slowed down seamer to make it un-noticable. One in a while he would have let it rip with full pace. I think the cricket vocabulary during Barnes' time was very poor, and what the writers meant with certain phrases may not be the same thing used today