Current is the chief essential for successful clam culture. The term "current" does not imply a rapid flow of water, but rather a good circulation of water over the flat. In the Essex and Ipswich rivers the clam flats have a continuous current. On such flats the growth is more rapid than on flats which have no circulation of water, in addition to the mere rise and fall of the tide. The current performs the work of (1) keeping the flats clean and carrying away all contamination, but its most important work is as (2) _food carrier_. _Value of a Clam Farm._--The value of an acre of clam flats, if properly cultivated, is about $450 per year for the average clam flat. Many of the more productive flats will yield a far greater amount, while others will not yield as much. It has been often erroneously stated that an acre of clam flats would produce $1,000 per year. This is a decided overestimation, as it would be hardly possible for the most productive flat to yield that amount. It is possible, however, for a good flat to yield about $750 per year, but this is only under the most favorable conditions. Such yields as these are large for the clammer, whose average yearly income is only $400 (a few of the more expert clammers make possibly $700 to $750), and a man possessing a clam farm of 1½ to 2 acres would make a good living. _Method of operating a Clam Farm: choosing the Ground._--In choosing a grant, the planter should have in mind three things: (1) the accessibility of the grant, for his own convenience, and nearness to the market, as much of the success of clam farming depends upon the expense of marketing the product, and the ease with which it can be disposed of; (2) the length of time allowed for labor by the exposure of the flat (flats vary greatly in the amount of time exposed each tide, the low flats being submerged nearly all the time, and the high flats having a much longer exposure),--a high flat possesses the advantage of allowing a longer working period for the clammer; (3) the natural facilities of the flat itself as regards the growth of clams. Moreover, the flat should be chosen in regard to (1) soil; (2) current; (3) tide. A good flat should have a soil which is tenacious and compact, affording at the same time easy digging. Probably the best soil is a mixture of fine sand and mud in a ratio of one-third mud to two-thirds sand, as this amount of mud gives the right degree of tenacity.