Mr. Butterfield, in making of the globules, used a lamp with spirit of wine; but instead of a cotton wick, he used fine silver wire, doubled up and down like a skain of thread.[10] He prepared his glass by beating it to powder, and washing it very clean; he then took a little of this glass upon the sharp point of a silver needle, wetted with spittle, and held it in the flame, turning it about till a glass ball was formed; then taking it from the flame, he afterwards cleaned it with soft leather, and set it in a brass cell. [10] Philos. Trans. No. 141. No person has carried the use of these globules so far as Father Di Torre, of Naples, nor been so dexterous in the execution of them; and if others have not been able to follow him in the same line, it may be fairly attributed to a want of that delicacy of touch for adjusting the objects to their focus, and that acuteness of vision which can only be acquired by long practice. Di Torre has also described, more minutely than any other author, the mode of executing these globules, which, as it throws much light upon the preceding description by Dr. Hooke, will not, it is presumed, be unacceptable to the reader. Three things are necessary for forming of these globules: 1. A lamp and bellows, such as are used by the glass-blowers. 2. A piece of perfect tripoli. 3. A variety of small glass rods. When the flame of the lamp is blown in an horizontal direction, it will be found to consist of two parts; from the base to about two thirds of its length, it is of a white colour; beyond this, it is transparent and colourless. It is this transparent part which is to be used for melting the glass, because by this it will not be in the least sullied; but it will be immediately soiled, if it touch the white part of the flame. The part of the glass which is presented to the flame, ought to be exceeding clean, and great care should be taken that it be not touched by the fingers. If the glass rod has contracted any spots, it must either be thrown away, or the parts that are spotted must be cut off.