摘要
In order to see if the 11-year solar activity could cause measurable variation in △<sup>14</sup>C concentration of atmosphere, we measured （cooperating with Chen Tie-mei, Yun Si-xun and Fan Chang-yun） the <sup>14</sup>C contents △<sup>C</sup> in AD1824—1925 tree rings of a white spruce, growing at the Mackenzie Delta（68°N,130°W） in Canada. The results are listed in Table 1.
