In the main Gregory's conclusions seem to be well grounded, although even according to his data a change of 2 deg. or 3 deg. in mean temperature would be perfectly feasible. It will be noticed, however, that they apply to temperature and not to rainfall. They merely prove that two thousand years ago the mean temperature of Palestine and the neighboring regions was not appreciably different from what it is today. This, however, is in no sense out of harmony with the hypothesis of climatic pulsations. Students of glaciation believe that during the last glacial epoch the mean temperature of the earth as a whole was only 5 deg. or 6 deg.C. lower than at present. If the difference between the climate of today and of the time of Christ is a tenth as great as the difference between the climate of today and that which prevailed at the culmination of the last glacial epoch, the change in two thousand years has been of large dimensions. Yet this would require a rise of only half a degree Centigrade in the mean temperature of Palestine. Manifestly, so slight a change would scarcely be detectable in the vegetation. The slightness of changes in mean temperature as compared with changes in rainfall may be judged from a comparison of wet and dry years in various regions. For example, at Berlin between 1866 and 1905 the ten most rainy years had an average precipitation of 670 mm. and a mean temperature of 9.15 deg.C. On the other hand, the ten years of least rainfall had an average of 483 mm. and a mean temperature of 9.35 deg.. In other words, a difference of 137 mm., or 39 per cent, in rainfall was accompanied by a difference of only 0.2 deg.C. in temperature. Such contrasts between the variability of mean rainfall and mean temperature are observable not only when individual years are selected, but when much longer periods are taken. For instance, in the western Gulf region of the United States the two inland stations of Vicksburg, Mississippi, and Shreveport, Louisiana, and the two maritime stations of New Orleans, Louisiana, and Galveston, Texas, lie at the margins of an area about 400 miles long. During the ten years from 1875 to 1884 their rainfall averaged 59.4 inches,[30] while during the ten years from 1890 to 1899 it averaged only 42.4 inches. Even in a region so well watered as the Gulf States, such a change--40 per cent more in the first decade than in the second--is important, and in drier regions it would have a great effect on habitability. Yet in spite of the magnitude of the change the mean temperature was not appreciably different, the average for the four stations being 67.36 deg.F. during the more rainy decade and 66.94 deg.F. during the less rainy decade--a difference of only 0.42 deg.F. It is worth noticing that in this case the wetter period was also the warmer, whereas in Berlin it was the cooler. This is probably because a large part of the moisture of the Gulf States is brought by winds having a southerly component.