the general trends that occur in the high-resolution $J$-band data as a function of spectral type. A convenient way of doing this is to select a representative source for a few spectral types and present all eight echelle orders on the same plot, thus enabling the entire $J$-band to be viewed at a glance. Figures 1$-$6 show the reduced spectra of Wolf 359 (M6), 2MASS 0140+27 (M9), 2MASS 0345+25 (L0), 2MASS 1507$-$16 (L5), SDSS 0423$-$04AB (T0) and 2MASS 0559$-$14 (T4.5). The double nature of SDSS 0423$-$04AB means that we do not have a true T0 spectrum, but lower resolution studies (M03) show that J-band spectral variations are relatively weak from L6 to T2 and therefore this binary remains a useful proxy for a T0 dwarf. In these plots, echelle orders 58 through 65 are shown together; the remaining orders at the edges of the $J$-band are too contaminated by strong atmospheric absorption to be useful. For ease of comparison, all spectra are shown in the laboratory reference frame and vacuum wavelengths are used throughout; radial velocities and searches for radial velocity variations will be reported and discussed in a separate forthcoming paper (Prato et al. 2006 in prep.). Each order 