A timely and plausible investment plan keyed to the interest-rate cycle. Coslow, founder of the respected financial newsletter, Indicator Digest (and a songwriter of some renown), sets forth a four-phase program. As interest rates rise (Stage I), he recommends investing in money-market funds ""and very little else""--i.e., neither stocks nor bonds fare well in that environment. When rates plateau (Stage II), turn to money-market instruments: Treasury bills, commercial paper, and other high-yielding commitments of comparatively short maturity. As interest rates begin to decline (Stage III), lock in the peak returns typically available on intermediate-term Treasury obligations and triple-A corporate debt. When rates bottom out (Stage IV), shift to Canadian T-bills (generally higher-yielding, for one thing, than their US counterparts), electric-utility shares (whose dividends--thanks to a quirky accounting rule--are tax-sheltered), and a handful of mutual funds with consistently superior records. To make successful use of Coslow's system, investors must be able to call turns with a fair degree of accuracy--which means diligent attention to the course of short- and long-term interest rates. Trends should be checked, moreover, against other benchmarks: activity in the automotive and construction industries (because they influence so many fields)--plus the CPI and federal funds rates. With some thoughts on the overall perils of elevated interest rates (Coslow would peg them, via a National Usury Law, no higher than 13-14 percent): useful and ponderable.