<P> To determine the chemical composition of seawater at various depths from the surface to the bottom, the organic matter in solution and the particles in suspension . </P> <P> To ascertain the physical and chemical character of deep - sea deposits and the sources of these deposits . </P> <P> At each of the 360 stations the crew measured the bottom depth, temperature at different depths, observed weather and surface ocean conditions, and collected seafloor, water, and biota samples . </P> <P> Challenger's crew used methods that were developed in prior small - scale expeditions to make observations . To measure depth, Challenger's crew would lower a line with a weight attached to it until it reached the sea floor . The line was marked in 25 fathom intervals with flags denoting depth . Because of this, the depth measurements from Challenger were at best accurate to 25 fathoms, or approximately 45m . The sinker often had a small container attached to it that would allow for the collection of bottom sediment samples . </P>

What three types of samples were collected by hms challenger between 1872 and 1876