<±×¸² 2> ÃÖÃÊÀÇ ÄÚ´Ú Ä«¸Þ¶óÀÇ ·Ñ Ȧ´õ ¸ÞÄ¿´ÏÁò. ÁÂÃø¿¡ ¿øÇüÀÇ ÃÊÁ¡¸é Á¶¸®°³°¡ º¸Àδ٠(Scientific American, September 15, 1888, p. 164).