From the point of view of the tropical resident, it is unfortunate that some of the tables in this publication are hardly carried high enough, but the instructions will enable anyone to amplify them. On this account, I append a table for calculating relative humidity of a less elaborate sort, but more extended than that furnished in the pamphlet, as this is one of the most important of all climatic factors from a sanitary point of view. The table is only worked out to half degrees of difference between the wet and dry bulb instruments, and for the most part to 4° intervals of the dry thermometer, but it is easy, by reading between the lines, to fill up the gaps, where any marked interval exists; and it will be observed that at the lower right-hand corner of the second table, the numbers progress in regular arithmetical progression, so that it is not difficult to infer the percentages in cases of somewhat higher degrees of temperature and dryness. TABLE FOR CALCULATING THE RELATIVE HUMIDITY OF THE ATMOSPHERE % BY THE DRY AND WET BULB THERMOMETER. ==========+======================================== Difference| READING OF THE DRY BULB THERMOMETER. of Wet +---+---+---+---+---+---+---+---+---+---+ and Dry | | | | | | | | | | | Bulbs |32°|34°|36°|38°|40°|44°|48°|52°|56°|60°| ----------+---+---+---+---+---+---+---+---+---+---+ 0·5 | 92| 94| 95| 95| 96| 96| 96| 96| 97| 97| 1 | 87| 89| 91| 91| 92| 92| 92| 93| 93| 93| 1·5 | 81| 84| 86| 87| 88| 88| 88| 89| 89| 90| 2 | 76| 80| 82| 83| 84| 84| 85| 86| 87| 88| 2·5 | 70| 75| 78| 79| 80| 81| 82| 83| 83| 84| 3 | 65| 71| 74| 76| 76| 78| 79| 80| 81| 82| 3·5 | 60| 66| 70| 72| 73| 75| 76| 77| 78| 79| 4 | 56| 62| 66| 69| 70| 72| 73| 74| 75| 76| 4·5 | 52| 58| 62| 65| 66| 69| 70| 71| 72| 74| 5 | 48| 55| 59| 62| 63| 65| 67| 69| 70| 71| 5·5 | 45| 52| 56| 59| 61| 62| 64| 65| 67| 69| 6 | 41| 49| 53| 56| 58| 60| 62| 63| 65| 66| 6·5 | 38| 46| 50| 53| 55| 57| 59| 61| 62| 64| 7 | 35| 43| 47| 50| 52| 55| 57| 59| 60| 62| 7·5 | 32| 40| 44| 48| 49| 52| 54| 56| 58| 60| 8 | 30| 37| 42| 45| 47| 50| 52| 54| 56| 58| 8·5 | 29| 35| 40| 42| 44| 48| 50| 52| 54| 56| 9 | 27| 33| 38| 41| 42| 46| 48| 50| 52| 54| 9·5 | 25| 31| 36| 38| 40| 43| 46| 48| 50| 52| 10 | 23| 30| 34| 36| 38| 41| 44| 46| 48| 50| 10·5 | 21| 28| 32| 34| 36| 40| 42| 44| 46| 48| 11 | 19| 26| 30| 32| 34| 38| 40| 43| 45| 46| 11·5 | 17| 24| 28| 30| 32| 36| 38| 41| 43| 45| 12 | 16| 23| 27| 29| 31| 34| 36| 39| 41| 43| 12·5 | 15| 21| 28| 27| 29| 32| 34| 37| 39| 42| 13 | 14| 20| 24| 26| 28| 31| 33| 36| 38| 40| 13·5 | 13| 18| 23| 25| 27| 30| 32| 35| 36| 38| 14 | 12| 17| 22| 24| 25| 28| 30| 33| 35| 37| 14·5 | 11| 16| 21| 22| 24| 26| 29| 31| 34| 36|