Baltimore, Md. For each block of 1,000 social security account applications 'work' cards are prepared. One work card is made for each operation incident to seeting up individual accounts and necessary indexes. The photograph above shows a worker in the Social Security Board Records Office at work at the 'visible control' rack. Each card in this rack represents an operation completed on one block[?] of applications. By glancing at each compartment in the rack, the number of operations completed can be estimated at once