**Traditional Engine Order Telegraphs:** The bridge unit and the engine-room unit are connected by two chains (or wire cables) that run through conduits over sprockets, forming a continuous loop. When the bridge officer moves the handle, it turns a sprocket that pulls the chain, which in turn turns the corresponding sprocket and pointer in the engine room. This classic system does not require electricity; it relies on a direct physical linkage, ensuring that both dials always mirror each other. Here’s a typical sequence of operations: The bridge officer grabs the handle and swings it to the command position, for example, "Half Ahead." This movement not only moves the engine-room pointer but also rings a bell or gong to alert the engineers. The engineers then adjust their own handle to match the position indicated by the bridge officer; this movement serves as an acknowledgment and rings the bell back on the bridge, confirming that the order has been received and understood. Only after this acknowledgment do the engineers work the throttle and reversing gear to carry out the order. It is common practice to first execute a full sweep of the handle, moving it all the way to one extreme and back before settling on the actual command position. This exaggerated motion serves two purposes: it rings the gong loudly and unmistakably, ensuring everyone is aware that a new order is coming, and it checks that the mechanism and chains are not stuck or slack. On some ships, this full sweep also signifies an important or urgent change (such as switching from ahead to astern), emphasizing to the crew that they need to pay attention because the situation is critical. After completing this sweep, the handle is adjusted to the desired position. This telegraph is from the Steamship Shieldhall (video credit as well). Go check her out on ss-shieldhall.co.uk/