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Two obsolete pharmaceutical weights differing threefold, distinguished on paper by where a stroke crosses.
A dram is three scruples. On the page the two symbols are built from the same looped stroke and differ in where a second stroke crosses it, so a hurried hand or a poor copy could turn one into the other and a threefold dosing error with it. Both are obsolete in dispensing, replaced by metric units during the twentieth century, and this pair is the clearest argument for why.
The two signs differ only in where a stroke crosses, between units differing by a factor of three.
| Apothecary dram sign | Apothecary scruple sign | |
|---|---|---|
| Relative magnitude | Three scruples. | One third of a dram. |
| What distinguishes the glyphs | The position of a crossing stroke. | The position of a crossing stroke. |
| Current status | Obsolete in dispensing. | Obsolete in dispensing. |
| Relationship (from Symbolwise's records) | Commonly confused with Apothecary scruple sign — The two signs differ only in where a stroke crosses, between units differing by a factor of three. | Commonly confused with Apothecary dram sign — The two signs differ only in where a stroke crosses, between units differing by a factor of three. |
Pharmaceutical notation, apothecary weights and prescription abbreviation
The pharmacopoeia commissions and pharmacy history scholarship · retrieved 2026-08-27
Cited for the identity and historical use of apothecary symbols and prescription abbreviations. Nothing here is clinical or dispensing guidance, and several abbreviations recorded are deprecated precisely because they were misread.
The becquerel counts nuclear decays — one per second — and says nothing about harm. The sievert weights absorbed energy by the kind of radiation delivering it, and so estimates biological effect. A becquerel of one isotope and a becquerel of another can carry very different risk, which is exactly why exposure limits and medical doses are stated in sieverts and never in becquerels.
Count what is around the centre. Three solid blades radiating from a small disc is ionising radiation; three broken rings overlapping a central circle is biological hazard. They are the same size, the same colours and the same three-fold arrangement, which is why signage catalogues themselves get them wrong — and the responses could not be less alike. One calls for distance, shielding and time; the other for containment, disinfection and a disposal route.
The FDI system gives each tooth two digits — the first the quadrant, the second the position from the midline — and is spoken as two separate digits, so tooth one-six is the sixth tooth of the first quadrant. The Universal system numbers the permanent teeth straight through from one to thirty-two around both arches. Sixteen means different teeth in the two systems, so a bare number is ambiguous unless the convention is named with it.
The skull warns about a single exposure that can kill or seriously harm now. The silhouette with the starburst warns about what repeated exposure does over years — cancer, genetic damage, harm to fertility or an unborn child, damage to an organ, or the danger of a liquid entering the lungs. Substituting one for the other changes whether the control needed is a spill procedure or decades of health surveillance, which is why this is the most consequential confusion in the set.