| Month. | Deaths. | Month. | Deaths. | |
| January | 541 | July | 1,433 | |
| February | 475 | August | 1,126 | |
| March | 476 | September | 791 | |
| April | 554 | October | 522 | |
| May | 584 | November | 460 | |
| June | 798 | December | 504 |
It appears that during eight months of the year, excluding June, July, August, and September, the average monthly mortality from "zymotic diseases" was 452. Had the same average continued during the remaining four months the total mortality from those diseases for that year would have been 4,424; but the actual mortality was 7,764, which proves that 3,340 persons were sacrificed during those four fatal months to conditions which exist in the city only at that period of the year. Still more startling is the estimate of the sickness rate caused by the unhealthful conditions created in the summer months in New York city. If we estimate that there are twenty cases of sickness for every death by a zymotic disease there were 66,800 more cases of sickness in the year above referred to than there would have been had the sickness rate been the same in the summer as in the other months of that year.
One of the saddest features of this high sickness and death rate appears when we notice the ages of those who are especially the victims of these fatal diseases. During the week ending July 9th last there were 399 deaths from diarrhœal diseases, of which number 382 were children under five years of age. The following table taken from the records of the Health Department show in a very striking manner how fatal to child life are the conditions peculiar to our summer season:
| Month. | DEATHS FROM DIARRHŒAL DISEASES. | |||
| Under one year. | Under two years. | Under five years. | All ages. | |
| January | 50 | 55 | 58 | 82 |
| February | 47 | 51 | 58 | 75 |
| March | 75 | 80 | 83 | 96 |
| April | 82 | 91 | 97 | 108 |
| May | 101 | 117 | 121 | 104 |
| June | 387 | 430 | 436 | 467 |
| July | 809 | 990 | 1,020 | 1,100 |
| August | 464 | 565 | 697 | 762 |
| September | 267 | 394 | 409 | 462 |
| October | 114 | 148 | 154 | 190 |
| November | 59 | 70 | 72 | 89 |
| December | 57 | 62 | 64 | 82 |
These statistics demonstrate the extreme unhealthfulness of New York during the summer, and the vast proportion of children who perish from the fatal agencies which are then brought into activity. It is a matter of great public concern to determine the nature of the unhygienic conditions on which this excessive mortality depends, and thus discover the proper remedial measures.
As high temperature is the distinguishing feature of the summer months, we very naturally conclude that excessive heat is a most important factor, if not the sole cause, of the diseases so fatal to human life at this period. A close comparison of the temperature and mortality records of any summer in this city demonstrates the direct relation of the former to the latter. For illustration, we will take the records of the Health Department during the past summer, selecting diarrhœal diseases for comparison, as they prevail and are most fatal at that season of the year. The table gives the total mortality from these diseases and the mortality from those diseases of children under five years of age. To the four months, June, July, August, and September, are added May and October, for the purpose of showing the gradual increase of the mortality from these diseases as the hot weather approaches and its decline as the hot weather abates.
| Week ending | Total diarrhœal diseases. | Diarrhœal diseases under five yrs. | Mean temperature (Fahrenheit) | Maximum temperature (Fahrenheit) | Minimum temperature (Fahrenheit) |
| May 7th | 10 | 8 | 52.4° | 72° | 47° |
| May 14th | 20 | 17 | 55.5° | 71° | 40° |
| May 21st | 14 | 12 | 63.3° | 86° | 52° |
| May 28th | 22 | 19 | 60.9° | 70° | 56° |
| June 4th | 18 | 16 | 65.8° | 76° | 54° |
| June 11th | 26 | 20 | 71.6° | 86° | 58° |
| June 18th | 36 | 32 | 73.0° | 89° | 59° |
| June 25th | 74 | 69 | 69.3° | 94° | 54° |
| July 2d | 170 | 164 | 78.6° | 94° | 67° |
| July 9th | 399 | 382 | 77.4° | 100° | 61° |
| July 16th | 330 | 321 | 71.1° | 91° | 57° |
| July 23d | 388 | 356 | 77.4° | 91° | 67° |
| July 30th | 380 | 353 | 78.5° | 95° | 70° |
| August 6th | 380 | 353 | 78.8° | 92° | 67° |
| August 13th | 342 | 306 | 73.9° | 90° | 65° |
| August 20th | 290 | 261 | 74.8° | 89° | 64° |
| August 27th | 268 | 246 | 76.6° | 93° | 63° |
| September 3d | 289 | 256 | 79.0° | 93° | 59° |
| September 10th | 283 | 255 | 74.0° | 92° | 58° |
| September 17th | 179 | 158 | 67.3° | 85° | 52° |
| September 24th | 193 | 167 | 68.7° | 90° | 52° |
| October 1st | 132 | 117 | 66.5° | 80° | 54° |
| October 8th | 90 | 78 | 69.6° | 81° | 53° |
| October 15th | 71 | 58 | 60.1° | 74° | 49° |
| October 22d | 54 | 42 | 55.9° | 71° | 44° |
| October 29th | 39 | 32 | 53.9° | 67° | 41° |
Again, if we compare the temperature and mortality records for a series of days instead of months, it will be noticed that the mortality record follows the fluctuations of the heat record with as much precision as effect follows cause. The summer heat generally begins about the 20th of June and continues with varying intensity until the 15th of September. Within that period we can select many examples which strikingly illustrate the relations of temperature to mortality. For example, the first heated term of the year before us began on the 19th of June and lasted until the 26th of that month. The two records are as follows:
| Day. | Temperature. | Mortality. |
| 19th | 78° | 83 |
| 20th | 80 | 100 |
| 21st | 82 | 122 |
| 22d | 80 | 116 |
| 23d | 77 | 104 |
| 24th | 68 | 119 |
| 25th | 65 | 88 |