Burning the Candle at Both Ends Rushlights were made from the stem of the rush plants, dried and stripped of green fibre, then soaked in any available fat. Cheap and easy to make, they were a popular lighting option for poor people. The rush stem was supported in a holder at a 45 degree angle to provide maximum light and burn time. An average rush light burnt for 10 – 15 minutes. If you wanted a brighter light (but with half the burn time) you lit the rushlight at either end, hence the expression ‘burning the candle at both ends’.
more at Wikipedia. who supplies this photo
more at About.com.
I assumed this meant cat tail stalks, but what is a rush?
RUSH PLANTS from Brittanica.com
rush, any of several flowering plants distinguished by cylindrical stalks or hollow, stemlike leaves. They are found in temperate regions and particularly in moist or shady locations. The rush family (Juncaceae) includes Juncus, the common rushes, and Luzula, the woodrushes. Common rushes are used in many parts of the world for weaving into chair bottoms, mats, and basketwork, and the pith serves as wicks in open oil lamps and for tallow candles (rushlights). J. effusus, called soft rush, is used to make the tatami mats of Japan. The bulrush, also called reed mace and cattail...
more HERE (Pilgrim, a british site).
Rushlights were the most common source of light in the cottages of Wales until the beginning of the 20th century. The soft rush (Juncus effusus) or common rush (Juncus conglomeratus) were the species of plant used for the purpose, which was found growing in pastures and beside streams. The longest and largest rushes were chosen and gathered in the summer when they were green. They were then soaked to prevent shrinkage and to make the peeling easier. After being peeled they were dried and then soaked in a grease-pan of boiling fat.
So what is Juncus effusus? From Missouri Botanical gardens.
Soft rush or common rush (also bog rush or mat rush) is a grass-like, rhizomatous perennial that features cylindrical upright green stems in spreading basal clumps to 20-40” tall. Clumps provide vertical accent to moist garden areas. Although the stems appear from a distance as coarse and stiff, they are soft to the touch. Soft rush is native to North America, Europe, Asia, Africa, Australia and New Zealand. In many locations it is considered to be a somewhat aggressive weed. Juncus effuses var. solutus is commonly found in central and southern Missouri in stream margins, sloughs, ponds, wet depressions in fields, pastures and prairies and in roadside ditches (Steyermark). Soft rush is one of the true rushes. The plant leaves are reduced to bladeless sheathing at the stem bases. Insignificant, tiny, yellowish-green to pale brown flowers appear in clusters (many flowered cymes) that emerge on the side of the stems slightly below the stem tips in summer. Foliage turns yellow in fall before browning up for winter. Soft rush is commercially grown in Japan for making tatami (woven mats for homes). From ancient times until the early 1900s, soft rush stems were used in England to create inexpensive, candle-like evening lights called “rushlights.” Rush stems were peeled away and the inner pith was soaked in animal fat, grease or wax. When dry, the pith could be lit at one end (sometimes both ends) and burned like a candle. Juncus means rush, and effusus means loose-spreading in probable reference to plant habit.
I haven't watched it, but NancyToday has a series of videos about making a rush light.