312 TRANSACTIONS OF THE HORTICULTURAL 



or the sums of the averagjes of daily observations; that the vegeta- 

 tive activity of the vine increases with an increase or elevation of 

 the temperature of the air surrounding it, up to a certain limit; that 

 the ])lossoms will open only when the temperature has attained an 

 average of 63° Fahrenheit; and that they will be fertile only if this 

 temperature be maintained until the fruit has set; that the same re- 

 lation holds for the interval between the opening of the bloom and 

 the maturity of the fruit. If the temperature be high the develop- 

 ment will proceed with greater rapidity and the fruit will ripen 

 early, while with a lower range of temperature this period will be ex- 

 tended. That the total sum of daily averages for the days interven- 

 ing between the opening of the buds and the full development and 

 njaturity of the fruit and its seed must reach about 7800° Fahren- 

 heit, at least, and with monthly averages of at least 60° Fahrenheit. 

 But even with all this, these authorities have been unable to satis- 

 factorily account for the differences between the good aud bad years 

 as dependent upon this influence. 



Levy made an extensive comparison of the records of tempera- 

 ture observations and the conditions of the grape crop as regards the 

 sugar and acid contained in the fruit, but he was unable to establish 

 any fixed relation between them. General observation and experi- 

 ence, however, teaches that those sections in which the temperature 

 is modified and regulated by surroundings, there the vine generall}^ 

 succeeds. We know that the celebrated vineyards of the Medoc are 

 located upon a low ridge protected from chilling winds of autumn 

 by the broad Gironde on one side and the Atlantic ocean on the 

 other; and that the same influences protect them in spring by so 

 cooling the air as to delay vegetation to such an extent as to place 

 it beyond the reach of spring frosts. The southern sunny slopes of 

 the Burgundy and Champaign districts, and of the Rhine, protect 

 their vines from chilling influences, and their products please the 

 world. 



The small lakes of Central New York, and the broad surface of 

 Lake Erie, provide similar influences at a latitude where the ordinary 

 climate almost wholly precludes the culture. Gasparin has shown 

 that the ripening of grapes ceases when the average temperature falls 

 below 54° F., and Davy shows that an average temperature of 58° F. 

 in the Champaign district from 1877-79, inclusive, was accompanied 

 by a bad result. So he considers the small crops of the same years 

 to have been caused by a low temperature of 53° F. during the period 

 of leafing out. 



In connection with the amount of heat required by the vine in 

 development, Marie-Davy, in his Agricultural Meteorology, makes an 

 interesting statement. He determines, in a general way, the number 

 of hours intervening during the annual development, and taking the 

 sum of thermometric degrees indicated for each hour, makes thus a 

 record of " hourly temperatures." Taking his figures based upon the 



