《徐霞客游记·粤西游日记二十一》
罗秀、卢塘之间，路旁有一棵空心树，高出地面一尺五，圆周大五尺，树洞中贮了一塘水，水面离树洞口有五六寸，下面浮出地面几乎一尺。
罗秀、卢塘之中，道旁有空树一圆，出地尺五，围大五尺，中贮水一泓，水面上盈树围者五六寸，下浮出地面者几及尺焉。
Between Luoxiu and Lutang, there is a hollow tree by the roadside, which is one foot and five inches higher than the ground, and has a circumference of five feet. There is a pool of water in the tree hole, and the water level is five or six inches from the entrance of the tree hole. The floating part of the ground is almost one foot.