The Visual Display

It was not unril rhe late 17oos thar dme-series charts began to
appear in scienrific wrirings. Thrs drawing ofJohann Hcinrich
Lambert, one ofa iong scries, shows the periodic variation in soil
tempcrature in relation ro the dcprh undcr rhe surface. The greater
the deprh, the greater the rime-1ag in temperature responsivencs.
Modern graphc dcsigns showing time-series periodicities diFer
little from those oflambert, although the data bases are far larger.
a
This plot of radio emissions from Jupiter is based on data collected
by Voyagcr 2 in its pass ciose by the planct in July 1979. The rrdio
inrensir;' increases and decrcases in a ren-hour cycle as Jupirer
rolates. Maximum intensity occurs when rLeJovian north magneric
polc is tipped roward fie spacecraft, indicating a norrhe
hemisphere source. A sourhern source was dctected on July 7, as
dre spacecraft neared the equatorial plane. The horizontal scale
shows the disunce of the spacecraft from the planet measured in
terms ofJupiter radii (R). Note the use ofdurl labels on the horizontal
to indicatc both the d:te and disr:nce fromJupirer. The
entire bottom panel also serves to label the horizontal scale,
describing the changing orientation ofthe spacecrafr relative to
Jupiter as the planet is approached. The multiple time--serics
erforce not only comparisons witLin each series over rime (as do
all time-series plots) bul also comparisons between the tluee
diferent sampled radio bands shown. Thn ricHy multivariare
display is based on 453,6oo instrumenr samples ofcight bits cach.
The resulting 3.6 million bits were reduced by pcak and average
p(ocessing ro rhe 18,9oo points acually plotted on thc graphic.
GRA?IIICAL IXCXTl!NCT 29
J. H. I-anberr, 4'o'err -l3ertin, r7?9).
D. A. clrneti, W. S. (u.th, and F. L.
sc2ri "Plasnx wave obs.rvarioDs Ncar
Jupite' Ihirial Rcsulrs f.om voy4er
2, s.tdra:06 (Novchb{ 2t, 19?e),
987 991; md Ietter from Dorold A.
Guhett to Edward R. Tufre, Jue 27,