Perhaps the medical man of this era, to whom the whole world is most indebted, is Dr. Jenner, who thoroughly investigated the wonderfully prophylactic powers of the cow pock. He had noticed that milkers of cows could not, as a rule, be inoculated with the smallpox virus—a means of prevention then believed in, as the patient generally suffered but slightly from the inoculation, and it was then a creed, long since exploded, that smallpox could not be taken twice. This fact of their resistance to variolous inoculation set him thinking, and he came to the conclusion that they had absorbed into their systems, a counter poison in the shape of some infection taken from the cows. He made many experiments, and found that this came from a disease called the cow pock, and that the vaccine lymph could not only be taken direct from the cow, but also by transmission from the patients who had been inoculated with that lymph, and whence the present system of so-called vaccination—the greatest blessing of modern times. Jenner, of course, was opposed; fools do not even believe in vaccination now, and great was the battle for, and against, in the medical profession, and many were the books written _pro_ and _con_. “Vaccination Vindicated,” Ed. Jones; “A Reply to the Anti-Vaccinists,” Jas. Moore; “The Vaccine Contest,” Wm. Blair; “Cow Pock Vaccination,” Rowland Hill; “Birch against Vaccination,” “Willan on Vaccination,” &c., &c. Gillray could not, of course, leave such a promising subject alone, and he perpetrated the accompanying illustration. Here Dr. Jenner (a very good likeness) is attending to his patients—vaccinating, rather too vigorously, one lady—the lymph, in unlimited quantity, being borne by a workhouse boy, and receiving his patients who are exhibiting the different phases of their vaccination. As a rule, they seem to have “taken” too well. [Illustration: THE COW POCK; OR, THE WONDERFUL EFFECTS OF THE NEW INOCULATION! (_Vide the publications of y[e] Anti-Vaccine Society._)] A quack, who flourished early in the century, far better deserved the caricaturists’ pencil than Jenner, and he got it. The illustration on this page represents an American quack, named Perkins, who pretended to cure various diseases by means of his metallic tractors—operating on John Bull. The paper on the table is the _True Briton_, and it reads thus: “Theatre—dead alive—Grand Exhibition in Leicester Square. Just arrived from America the Rod of Æsculapius. Perkinism in all its glory, being a certain cure for all Disorders, Red Noses, Gouty Toes, Windy Bowels, Broken Legs, Hump backs. Just discovered, Grand secret of the Philosopher’s Stone, with the true way of turning all metals into Gold.” [Illustration: METALLIC TRACTORS—1802.]