of clusters of galaxies which have been used to constrain the amplitude of the bulk flow on very large scales.

[lrll]{}\
Survey & $ N_{obj}$ & Type & Coverage\
\
Aaronson & 300 & spirals & all-sky\
Tonry & Davis & 300 & early & north\
7 Samurai & 400 & early & all-sky\
Willick & 320 & spirals & Perseus-Pisces\
Courteau & 380 & Sb-Sc & north\
Mathewson & 2000+ & spirals & south\
SFI & 1300 & Sbc-Sc & all-sky\
ENEAR & 1600 & early & all-sky\
Shellflow & 300 & Sb-Sc & all-sky\
\
\

Early studies [@tonry-davis][@aaronson] focused on the properties of the flow field near Virgo. However, it was soon realized that the assumption of a spherical infall was too restrictive and that Virgo alone could not explain the motion of the Local Group relative to the CMB. A major contribution to the field was the work of the 7 Samurai[@lynden-bell], the first to probe well beyond the local supercluster, albeit sparsely. Analyses of this sample led to startling results such as the measurement of a large amplitude bulk flow, and the discovery of the Great Attractor, a large mass concentration associated with the Hydra-Centaurus 