Several elaborations of this form are made, in which electrodes are sealed through the walls of the capillary tube, thus making it possible to detect electrically the variation of temperature when it exceeds any given limits. _An Enclosed or Floating Thermometer._--The construction of this type of thermometer is shown by _h_ and _i_, Fig 11. It is made in the following stages:--A bulb is blown on the drawn-out end of a thin-walled tube as shown by _h_. A small bulb is blown on the end of a capillary tube, burst, and turned out to form a lip which will rest in the drawn-out part of the thin-walled tube but is just too large to enter the bulb. The capillary tube is introduced and sealed in position, care being taken to expand the joint a little. The thermometer is filled and the top of the capillary tube closed by the use of a small blowpipe flame. A paper scale having the necessary graduations is inserted, and the top of the outer tube is closed as shown by _i_. _A Maximum and Minimum Thermometer._--If a small dumb-bell-shaped rod of glass or metal is introduced into the capillary tube of a horizontally placed, mercury-filled thermometer in such a position that the rising mercury column will come in contact with it, the rod will be pushed forward. When the mercury falls again the rod will be left behind and thus indicate the maximum temperature attained. If a similar dumb-bell-shaped rod is introduced into an alcohol-filled thermometer and pushed down until it is within the alcohol column, it will be drawn down by surface tension as the column falls; but the rising column will flow passed it without causing any displacement; thus the minimum temperature will be recorded. Six's combined maximum and minimum thermometer is shown by _b_, Fig. 11. In this case both maximum and minimum records are obtained from a mercury column, although the thermometer bulb is filled with alcohol. It is an advantage to make the dumb-bell-shaped rods of iron, as the thermometer can then be reset by the use of a small magnet, another advantage consequent on the use of metal being that the rods can be easily adjusted, by slight bending, so as to remain stationary in the tubes when the thermometer is hanging vertically, and yet to move with sufficient freedom to yield to the pressure of the recording column.