VII. When a large number of cases of this disease occur in rapid succession, in one individual's ordinary practice, and few or none elsewhere, these cases appearing in scattered localities, in patients of the same average condition as those who escape under the care of others, there is the same reason for connecting the cause of the disease with the person in this instance, as with the place in that last mentioned. VIII. Many series of cases, answering to these conditions, are given in this Essay, and many others will be referred to which have occurred since it was written. IX. The alleged results of observation may be set aside; first, because the so-called facts are in their own nature equivocal; secondly, because they stand on insufficient authority; thirdly, because they are not sufficiently numerous. But, in this case, the disease is one of striking and well-marked character; the witnesses are experts, interested in denying and disbelieving the facts; the number of consecutive cases in many instances frightful, and the number of series of cases such that I have no room for many of them except by mere reference. X. These results of observation, being admitted, may, we will suppose, be interpreted in different methods. Thus the coincidences may be considered the effect of chance. I have had the chances calculated by a competent person, that a given practitioner, A., shall have sixteen fatal cases in a month, on the following data: A. to average attendance upon two hundred and fifty births in a year; three deaths in one thousand births to be assumed as the average from puerperal fever; no epidemic to be at the time prevailing. It follows, from the answer given me, that if we suppose every one of the five hundred thousand annual births of England to have been recorded during the last half-century, there would not be one chance in a million million million millions that one such series should be noted. No possible fractional error in this calculation can render the chance a working probability. Applied to dozens of series of various lengths, it is obviously an absurdity. Chance, therefore, is out of the question as an explanation of the admitted coincidences. XI. There is, therefore, some relation of cause and effect between the physician's presence and the patient's disease.