RETURNS OF PREVALENT DISEASES.

In the tabulated summaries of monthly reports of the acute diseases most prevalent in the several towns, in each of the different months of the year, presented on the preceding pages, there is much to interest the sanitarian in noting the changing or apparent transmission of certain contagious diseases from one town to another; the persistence of the same and others in clinging to some one locality during the entire year; the various degrees of severity in which the different diseases appear in the different towns; the different relative proportions of prevalence in comparison of one disease with another; and many other aspects and phases of condition and circumstances appertaining to the appearance and continuance of the various diseases in the various sections of the State.

As stated in a previous report, if the returns of the prevalence of diseases in all the towns throughout the State, with the attendant circumstances, fully reported monthly, as desired by the Secretary, could be accomplished promptly and continuously, it would afford great facilities for studying the spread of the contagious and infectious diseases, in regard to the mode of transportation or travel; that is, whether they are communicated from one town to another in a direct line of travel as a rule, where communication is frequent and uninterrupted; or whether their mode of travel is by leaping over portions of territory as it were, and reappearing in towns or places at a distance, and not contiguous with those where they had prevailed at a time. immediately preceding.

If it should be found that any one of the contagious or infectious diseases which is in any important degree fatal to life, moved in any regular and straightforward path, it would be a fact of great value, as affording to those who were seemingly in its line of travel, an opportunity at least to prepare for its approach and presence, if it did not indeed afford the possibility of arresting its progress altogether. It is only by collecting a great number of observations, and a comparison of them when so collected, that the nature and characteristics of all diseases, whether transmissible or not, can be ascertained. And it is also by a great number of observations made in any town or section, and reported from time to time, that it can be determined, with any degree of accuracy, what diseases that town or section is especially liable to, and what means may be taken for their prevention or restriction.

It will be observed that in the tabulated summaries of monthly

returns, on the preceding pages, the columns of meteorological conditions, relative to temperature, humidity and fluctuations of the weather, as presented in the Second Annual Report of the Secretary, are omitted.

It was found by the results of observations during the year 1879, taken in various sections of the State, that the meteorological conditions of the different sections were quite uniform, the principal differences being in regard to humidity from summer showers.

It was therefore decided to make the mean average results of the observations taken in the vicinity of Providence city and in the city of Newport the mean average for the State. These have been collected, and with a monthly account of the fluctuations in relation to frequency and range of temperature, kept by the Secretary, the general results in each of the months, will be found in the following pages.

METEOROLOGY.

It was remarked in the Second Annual Report of the Board, in allusion to the monthly reports of meteorological observations made in the several towns in the State, that there were few differences of any magnitude in regard to mean humidity, or range, and frequency of change; and that in regard to mean temperature the monthly reports were also very uniform, and so continued through the year.

It was also remarked that the uniformity having continued so steadily through the twelve months of the year, it seemed to settle the question, presumably at least, that such observations made at two or three points, which would cover the possible differences between the meteorological conditions of the inland towns and those upon the bay and seashore, would answer for all practical purposes for all the towns in the State.

In order to present a general summary of the meteorological conditions prevailing throughout the State, in each of the several months of the year 1880, recourse has been had to the Signal Station at Newport, under charge of Col. Wm. McGillivray, Sergeant Signal Corps U. S. Army, and the office of the City Engineer of Providence.

The tables, kindly furnished from each of these sources, will be found on the following pages. The observations reported at the City Engineer's office in Providence were made at the City Hall, and at the pumping stations of the city water works in Providence and Cranston: